How to..Mercedes monovalve, duo valve cleaning,checking

[@lisajohnson8566]

Dude, you absolutely ROCK!!! When I opened the hood on my SLK this morning that valve was sitting right on the right inner fender panel, right out in the open. I electrical tested it and the "left" side didn't make a real click. The right side was a little better but there was clicking. I disassembled the valve EXACTLY like you shoed here and real actuators that you showed on your car were clean but the left side or the drivers control I could hardly get it out of the electrical coil. I got it out and it was full of gunk and gum. I carefully cleaned it and the "right" side valve and reassembled and my AC/Heat system works as good as new. This repair on my car took a total of 30 minutes and I lost just about a half a cup of coolant. I can't thank you enough as I was prepared for a HUGE bill to take this to someone for the repair. But thanks to you this worked as advertised and I can't thank you enough. As another poster said his location I'm in Oregon with a very cold air conditioner now. THANK YOU SO MUCH!!!!

[@zuiverskin]

I got the same issue and I'm also planning to get it fix. I'm thinking of doing this during the weekend. Just want to know when you clean your driver side valve. What is the tools or what do you need to clean? Fiber cloth or cloth can do the job?

[@lisajohnson8566]

Actually you just remove the screws that holds the top in place. The little plungers that move up and done will in my case had some what looked like antifreeze scale. I simply washed the parts in clean water and rubed the scale of with my fingers and reassembled. It's working fine ever since. I think these get stuck from "lack of use" meaning if you live mostly in a cold climate you set them for heat and that's where they stay. Likewise if you lived in a hot climate you'd be using the cold settings more. If they get exercised as in occasionally cycle your syster from the "usual" hot or cold setting you leave them on it will work to prevent the isssue. Hope this helps.

[@zuiverskin]

@@lisajohnson8566 OK. Will switch between hot and cold from time to let the switch get more exercise. ^_^

[@iliakupravishvli7157]

0000000000000000p000000000000000000000000000000000000000000000000000000000000000000000000000000000p000000000000000000000000000000000000000000000000000

[@boston16wrx7]

Did this after I noticed my heat wasn’t hot enough, went from 115 to 163 degrees!!! Another great video!!!!!

[@fupabox]

Good stuff!

[@petermarino2913]

Intermittent A/C with a bunch of codes, took apart the duo valve (as per your instructions) and cleaned the top and bottom plungers/valves with metal polish until they looked like a mirror. A/C back to full function. Mine were fully coated in that gold colored deposit as seen @2:38 - 2:46 Big Thanks fupabox!

[@fupabox]

very welcome..glad it helped :)

[@williamkennedy5492]

I have one side heat on my R129, its a 1989 model, at last i found the duo valve buried under the servo, i have heat on one side only, so using your video i will now take another look but first get an overhaul kit, winter is coming ( Nov 2023) and i will need some heat, best regards Cheshire UK

[@memeco50]

Thanks to videos like this I was able to fix the heater before the mild CA winter. Thank you all.

[@blackwell1384]

Thanks for the video. My car does not have dual zone heat, so it has only one solenoid. W124 1995. Your explanation saved me. It turned out the chrome on my piston had failed and it started to stick shut. I found a used solenoid and piston and I have heat. Thanks again

[@fupabox]

glad it helped

[@lisajohnson8566]

Great video and explaination. I apparently have the left side stuck wide open as all I get is HOT heat and the right side is trying to get cold so maybe the little valve is only partially stuck open. But I gather the system uses the AC all the time and moderates heat in to the cabin as needed. Interesting and simple concept for sure.. Appreciate the video.

[@teflonrich9886]

Hey did you ever find a fix, dealing with same problem on my s500

[@lisajohnson8566]

@@teflonrich9886It was exactly as explained in the video and a good google search lead me hear. Good luck!

[@123lolisch]

What kind of google search? Link?

[@1985safraz]

Your advice regarding the removal of duo valve helped me to safely remove, clean and put just the way it was and now cold air is coming through just got back from Iraq been off the road for almost two years and guess what started the first time

[@fupabox]

***** excellent..glad it helped you :)

[@victorsnip6734]

Thanks! I found out this morning while opening the piece. Not that much junk in the housing that stays in the car, but the plungers and all the other parts cleaned up; little but stuck thin "crusts...." Hope it will work again! Thanks again for the great video!!!

[@fupabox]

It doesn't take a lot of deposits to keep the valves from moving properly...hopefully it works for you

[@victorsnip6734]

It still doesn't work properly. And I can hear the electrical click when loosening the connector... Is there anything else to clean or look for if you know? Thanks!

[@fupabox]

Victor Snip are you getting heat inside the car? or no heat

[@victorsnip6734]

Most of the time no heat, only occasionally. I suspect the print behind the temperature wheels.... To be continued! ;-)

[@fupabox]

Victor Snip Ahh....with your car off..press the rest button on the climate control...it should turn the heat on with the car not running if it works you will hear it clicking/pulsing every few seconds it isn't a constant hum like a pump ..it pulses on and off to conserve battery power( useful in very cold winter days when you are running into a store and want a warm interior when you come back out) it can do this because there is an auxiliary boost pump to circulate coolant even with the engine off..it is electric and located on the side of the frame just below the coolant expansion tank (where the coolant is filled) it's sausage shaped with coolant hoses running in and out of it...it can block coolant from getting into the duovalve

[@tsdd.1567]

Thanks for the video. On my Mercedes the heating is working fine. However, the cooling is not working. Are these 2 valves related to the cooling system?

[@paulsiggins2995]

Thankyou so much, I've had four w124 estates they all ended up with this problem, I followed your instructions cleaned all the components, put it all back, instantly my heating works like a brand new car, the only other problem on my 93 300td is central locking not working on drivers door, when it works, if I lock from the passenger door, if you have a film on that you'd be a super star

[@fupabox]

I'm not very current on my w123 stuff.. but I did have this link in my files www.ifixit.com/Guide/Mercedes+W123+Vacuum+Lock+System+Diagnosis+Technique/20201

[@paulsiggins2995]

Thanks Again the link was really usefull explained the whole system clearly

[@JAZ.80]

I was amazed with amount of dry leaves laying around the a/c engine and that was making the mouse sound when i was turning on the a/c, I cleared it out and next to it I found the air filter, managed to extract that and it was loads of dust and leaves dried out there. After assembly my a/c works like a charm. no noise and the air flow is strong and smells clean :))) Thanks alot for the tips Fupabox!!!!

[@TheMikeHype]

Thanks. Solved my problem i‘ve had for 2 years.

[@FerPappalardo]

Thanks Fupabox. It really worked. The calefaction of my c230 was not working. I cleaned the duo valve and now working perfect. I save approximately $ 250. Thanks you very much.

[@fupabox]

that's great...glad it helped :)

[@motasralucamaria]

Great Video! Forgive me for butting in, I would love your opinion. Have you researched - Tarbbatigan Cars Rehabilitation Tip (google it)? It is a good one of a kind guide for learning how to repair your car the easy way minus the normal expense. Ive heard some decent things about it and my mate got amazing results with it.

[@marcosfabioealinegarcia3298]

Thanks for the video, helped solve my problem here in Brazil

[@zuiverskin]

I got the same issue and I'm also planning to get it fix. I'm thinking of doing this during the weekend. Just want to know when you clean your driver side valve. What is the tools or what do you need to clean? Fiber cloth or any cloth can do the job?

[@fupabox]

a microfiber or shop towel would be best to ensure no lint gets trapped .

[@zuiverskin]

@@fupabox Got it. Will give it a try this weekend. Thanks for sharing and clarify my concern. ^_^

[@quemavagabundos8813]

Can I turn off the heating with that hose? I have a leak and I don't know how to turn it off.

[@mikecontorno3504]

Your video shows the entire process except when you initially first take off the Dual valve cover the video cuts and then you already have the rods with the Springs out how do you get those out

[@giorgio2282]

@fupabox sorry, it's normal that my central vent has only cold and ac air? And no warm air?

[@ontariobill1]

Awesome job, i much prefer watching your videos to Mercedessource, I do like that you are precise, educated and polite, you must be Canadian.

[@fupabox]

Yessir.. Canadian ...appreciate the kind words :)

[@TheTaz069]

Nice quick vid. I just wanted to add on my plungers that pull up into the solenoids mine were stuck in the solenoids. I took some 1000 grit sandpaper lightly sanded to remove the old goop and residue, and cleaned the inside of the solenoids with some maf cleaner, just to remove the old goop. All good works like new.

[@ghejungky6581]

hello fupabox, I just saw your video. does this affect the unstable RPM drop

[@russellbshoes1470]

Great video clear picture and sound..

[@farerse]

is this what we actually control when we select temperature inside the car?

[@BAYATULL1]

Buna ziua am o problemă imi funcționează doar pe o parte căldură pe cealaltă parte imi dă rece. Va mulțumesc frumos. As dori daca se poate câteva sfaturi. Menționez ca o dau pe cald amândouă zone

[@paulattree4171]

Im in the UK . have a clk 320 cabrio 1999. Without your videos i would have to get a bank loan to pay a mechanic for the repairs you do. Thankfully you have a video for every fault mine suffers or sufferd with. Excellent stuff. Pls keep your car it helps me alot when yours goes wrong. LOL

[@fupabox]

lol...I'm glad the vids help

[@ukiarni5011]

A czy te zawory maja klikac co chwilkę podczas ich pracy? Mam problem bo gdy włączam ogrzewanie to węże wodne od silnika zaczynają pulsować az nimi trzesie. Jeśli wyłączę wentylacje na OFF przestaję. I nie wiem czy to nie wina tych zaworów . kzbin.info/www/bejne/Y5uqpY2aj9V5f5Isi=w8HK18QaDUvwInGK Jak wyłączę ogrzewanie /wentylację efekt ustaje .

[@JAZ.80]

Hi Fupabox ? Thanks alot ! your videos are amazing. I am so happy you have a Class :) In a country where mercedez dealers charge US$ 220/hour of labour and black market mechanics charge average of US$ 100/hour your how to Videos are becoming Gifts :) Thanks alot man!!!

[@ralphmorris7781]

From UK , thanks 🙏 v helpful and £ saving

[@virendrasharma4171]

Thanks for well explained valve demo it solved my probs this car is parked more less on road .👍👍good luck

[@mrtakemytyme7162]

I have a question w208 clk 320 my ac clutch kicks on blows hot air put can with recharge gage attached say it over charge so I release the pressure keep releasing till compressor stops put can back to gage says low but when u try ti put charge back in it shoots to red with barley squeezing the release I'm stumped what to please help of possible

[@robertsekrst8020]

Hi fupabox. I have a another nightmare problem with my CLK 200 kompressor, 163 HP engine M111.344 . Automatic 2 zone AC . Only one big cooling E-fan. The problem is that the electric cooling fan goes occasionally to full speed at random intervals but the engine is for example cold and the air vent flaps open and close in random manner. As soon as I turn OFF the AC/heater unit altogether the cooling fan works normally, and kicks in at about 85 C temperature. AC error codes are B1459 and B1423, B1416 (416 is the aux cooling pump and is not related to the problem because its not working for 2 years, carbon brushes worn out) . It seems as a problem with Y11 switch over valve or a short circurt. I can erase the code but they are coming back. Can I perform a vacuum test ? The air flaps are working fine. Another OBD scanner shows B1100 and B112E code. Just a side note. While replacing the camshaft magnet I broke of the cooling temperature sensor (only the plastic connector broke but the pins where OK so i just used crazy glue to fix it). Might this be the culprit of the problem ? The temperature gauge however shows the correct temperature so I assume its working fine. I also noted a few knocks from the left duo valve for a coupe of seconds upon startup. Temperature hot cold is working OK for both zones. Should i clean and check it anyways ? How can i test and troubleshoot the problem ? Please help . BR

[@fupabox]

I would clean and lube the duo valve just for good maintenance , but I don't think that is the problem . I would start with the coolant temp sensor and the cooling fan resistor . The temp sensor signals the resistor to turn the fan on , So I would start there

[@nomebear]

The Duovalve plungers are available on Ebay, and new, and that included the rubber gasket. Mine came from Russia.

[@fupabox]

great info..thanks

[@PureVoice_cz]

Perfect helpful video. Thank you.

[@fupabox]

You're welcome!

[@carlosdanieldias1341]

Hi, the shaft of my plungers have broken. Is it the shaft of the plungers that comes up and down sliding in the other shaft or ar they magnetized and come up and down with the shaft of the coil, that brings them up and down? Because if they come up and down with the shaft of the coil I can glue them. Thanks

[@fupabox]

They need to be able to move freely within each other. The spring keeps them apart and water pressure allows them to kind of float up and down ,but not much. The magnet/solenoid locks the top plunger in place and now the lower can rise to let more coolant through . If you could re attach the shaft to its plunger it would be fine , but gluing both together wouldnt work. At least I don't think it would . I'm not %100 sure though. never tried it

[@marcusfinanger1116]

When I unplugged duovalve I only have cold air when plugged in I only have cold air. What's going on? I changed the duo valve since I thought it was bad but nothing changed. Any recommendations?

[@fupabox]

Check for vacuum leaks . Unfortunately the little actuator odd that change the vent flaps can have a bad diaphragm inside and not move the flap to allow warm air in . Also check your fuses to ensure that power is getting to the duovalve . You can check the plug on the duovalve with a multimeter and see if power is getting to it .

[@marcusfinanger1116]

@@fupabox Okey thanks

[@quemavagabundos8813]

Is that where the air conditioning antifreeze goes?

[@stanberman9324]

On my 1998 SLK230 there is no clicking when I connect and disconnect the wires. Do you know which fuss to check? The right heater vent is stuck in the on position so it blow hot air as soon as the engine heats up after about a minute, even if I have the a/c on for the left vent.

[@fupabox]

15,33,36 anything listed as tempmatic .. could also be a wonky k40 relay in the electronics black box in front of the passenger windshield by the firewall

[@stanberman9324]

Thanks those fuses are ok. How can I get to the k40 relay and what do I do with it?

[@fupabox]

inside the big black plastic box in front of the passenger side windshield ..under the hood . Actually this vid would be easier to explain.kzbin.info/www/bejne/bWHFXn-AqMd5p80

[@carlosjaneira7774]

Estou em portugal e queriam levar-me 400€ pois diziam que precisava de novo. Limpei como ensinou e ficou OK. Muito obrigado.

[@andrieskgabedi5459]

my c230 is heating up inside when driving what could be the. In summer it gets very hot please help.

[@jakeweiman6157]

I have no heat on my w124. The hose going to to the monovalve is warm, and the valve itself is. the hose that goes to the cabin or beater core is cool to touch. think it's a clogged beater core? also, can flushing it with a garden hose hurt anything?

[@fupabox]

no, you can safely flush it

[@zahari_s_stoyanov]

Been wondering why it blows cold on the driver's side(the temps are set to MAX on both sides)... Tonight my side of the windshield fogged up really bad and I had to drop the temp on the passenger's side. I hope this clean-up can solve the issue :D

[@brianwilson917]

Following the instruction, the only thing that was different, is the area where the brass needle valves are seated was full of anti freeze. I tried to get the anti freeze out using paper towels to soak it up, but it just kept filling with anti freeze. I wanted to be sure that the needle seats were in good shape. Any idea why it kept filling up with anti freeze? Your video showed them dry?

[@fupabox]

possibly pressure in the system pushing coolant out . If you remove the coolant bottle cap it should stop the pressure

[@brianwilson917]

@@fupabox That was my original thought, so I loosened the cap, and actually got more AF flowing. Anyway, it is back together and all is working fine. I finally have heat, and before, the only heat was the defroster.

[@tempest411]

Hello, Would you care to guess why the front defroster in my wife's '98 C230 goes to full hot when activated? The fan speed, which goes to full speed can be lowered manually, but the temperature can not. Even at low speed, the interior of the car gets WAY too warm after a short while. The A/C doesn't seem to work very well either, as if the control unit has a mind of it's own...could it be that (the control module in the dash)? Thank you!

[@fupabox]

the default for the front defrost is "HI" temp...it can't be adjusted...once you get the windshield defosted, set it to auto..or manually on the seat pictogram set the arrow to up..which will put adjustable air to the windshield....the defrost button is only for rapid defrost of the windshield...it is not a normal setting use setting like on most cars...set the temperature, and press the auto button and it will be the best at keeping it all clear

[@kowal116]

Hi. I have different problem on my w124, no AC. It only blows hot air. There is aprox 14v on pins when set temp to minimum, valves are clicking. When to max they are not clicking and no voltage. So electrically is fine. Plungers are not broken, only a bit rounded on the "heads". everything cleaned. Where is the problem?

[@trixie9867]

wow you love your duo valve

[@jessc8173]

that solenoid check made things easy

[@fupabox]

+Jess C very welcome

[@ayazkamal123]

Hello, I have a SLK 230, 1998 ... my heater works intermittently. i tried to open the duo valve and it looked like some kind a oil was coming out so i put the screw back...i don't know if i should open it and clean the valve.

[@fupabox]

Yes you can open it and clean the valve.. likely it is just old crud stuck in there

[@marcosfabioealinegarcia3298]

Dear friend, if I remove this valve, no need to have hot air in the car, here in Brazil is very hot, if I remove the valve and close the hoses have a problem? Because water passes through them. Thank U

[@fupabox]

no.. no problem, if you don't need heat it's ok.. but they can't just be blocked off.. they can be re-routed to the intake side of the heater core

[@JAZ.80]

Now a small question for you.. My car (Mercedez C180 1998) make some crazy noise when i turn the AC on. sometimes its like you hear a mouse running inside the dashboard from driver side to passenger side. also recently i turn the AC on, but instead of cold air I get warm heated air .. i wonder if you have any idea what could possibily be the issue? Appreciate any tips. Thanks Jay

[@abdallahd.1505]

hey man thanks for your videos they're so helpful. and in my case when i turn the temp wheel to hot i'm not having very hot air and it's coming out only from my side vents,is it normal or it should come out of the center vent too? and could it be only this valve or maybe a clogged heater core? if yes can i flush it after disassembling the valve? and my other question is when i turn on the fan it takes time to start running is it a bad fan motor or resistor or it normally operates like that. appreciate your help :)

[@fupabox]

+abdalla Dar The center vent depending on the setting you have the climate control on, will mostly blow only fresh air..If the fan only takes a few seconds to come on ,that is normal..if it takes longer than a second or 2 then the brushes in the motor are worn...if the Temp won't get very hot on full..then yes a flush and or cleaning of the duo valve may solve it

[@abdallahd.1505]

+fupabox i'm gonna check it thanks a lot man appreciate it :)

[@bolipichi1]

Do you refer lubricate with some coolant are you referring just water?

[@fupabox]

Daniel Olmedo coolant is better

[@FabianCharrua]

'99 C280. The hose that connects to that, that goes down to the engine at the bottom sometimes pulsates like a heart beat. I also sometimes hear a pretty loud flap door closing under the dash glove compartment are. Any ideas?

[@fupabox]

Gerard Fabian Alvarez it's pretty normal...the pulsing is the recirc. pump..and the flaps opening and closing is just the system changing where it thinks the air should go to maintain temperature

[@Lemontech74]

I wonder if anyone could help: My air blows only hot in an R129. The monovalve ticks every couple seconds (if key is in position II, engine off, I can hear the ticks). I heard the valve is supposed to click/clunk loudly once. Would taking my valve apart be the next step, or is it a vacuum issue?

[@IraHayesIraHayes]

This would not prevent my blower motor and climate control from turning on right? It turns on sometimes after an hour when the car is warm...after the recirculation switch clicks and blinks for a few minutes....

[@fupabox]

it won;t stop the blower.. it just regulates water flow..if your fan won;t come it , it is likely a fan motor contact brush or fan resistor issue

[@victorsnip6734]

Hi! Great video!!! I only wonder where did you leave the connector, mounted with 4 cupper wires on the coils?

[@fupabox]

the connector was tucked unerneath

[@donnyhedge4472]

Ive got a 230 and i have large volumes of heat that comes out of passenger side defrost but little to no air out of drivers side. Help!! What do yall think?

[@fupabox]

likely the flap that controls the air to that side is stuck shut , the tube that feeds the air to it may be unhooked from that side,or the actuator may be broken or leaking...most likely the air supply tube is unhooked.. you can pull the gauge cluster out ( I have a vid on it in my w202 playlist) and check the connecting tube through there

[@williamkerdasha5273]

Thanks Fupabox for all the videos you make, several of them have helped me when working on my 1999 c280. I was wondering if you had any idea of what could cause a knocking noise behind the dash when the a/c is running. It sounds as if it is coming from the passenger side behind the dash.

[@fupabox]

one of the vacuum operated vent flaps is sticking or possibly jammed . Removing the panel above the passengers feet will allow a bit of access to see the flap actuator. The same panel to access the cabin filter

[@volandalorick3233]

I remove my duo valve. The metal plate was hard to remove but I got it. Everything looked good and was clean. I reassemble the duo valve and now I have a leak and the back left screw seems to be stripped because it's not tighten. Do I need to try and reassemble the duo valve or the replace the screw? Any advice??Thanks

[@fupabox]

LOL was just replying to the first comment..now .. OK so grab a slightly larger self tapping screw to replace that one.. Lowes Home Depot Autozone etc

[@volandalorick3233]

Do you know the size of the screw that are removed from the duo valve? Or have any idea what size I should get to replace the screw. Thanks so much for your help.

[@fupabox]

I don't know the exact size.. But if you go to Home depot with the screw , there is a little display in the screw section that you can use to find out the exact size. You can then just get the next larger size , which should be tighter within the hole.

[@volandalorick3233]

I replace the screw and so far so good. Thanks again I really appreciate your help. I also had to recharge my ac. It took the whole can within two mins. I'm going to get another one but I'm going to try the dye. Just in case I do have a leak. I will be able to locate the leak and fix it. Do you have any suggestions on this? I have a 99 c280.

[@fupabox]

get a cheap UV or black light on ebay or amazon (the ones they use to find nasty stains in hotel rooms) the dye will glow under black uv light . My ML uses a can of refrigerant each summer..If the A/C gets warm within a few weeks there is likely a sizeable leak somewhere ,that the UV light can help you find. Fingers crossed . Good work on the Duo valve ..you stuck with it and kicked its butt..persistence pays off . :)

[@ericcote3405]

Hello Futabox, just baught a 1998 c230, i'm having a problem with not enough heat coming out. Does cleaning these valves could solve this problem or the thermostat can alson be a problem? Thank in advance..

[@fupabox]

either could cause the problem... or both... if the engine temp gauge is normally between 85 and 95 degrees in heavy traffic, and around 80-90 on the highway..then your thermostat should be ok..... I would check the duovlave before spending $ on a new thermostst

[@ericcote3405]

Thanks, temp stick between 60 an 70 all the time...ill try the duo valve cleaning. Thanks very much. Ttyl

[@fupabox]

60 and 70 is very low..your fuel usage is probably a bit high as well..your thermostat is also likely causing the problem if your temp is that low

[@ericcote3405]

Thank you sir ! Do you have a video on how to change thermostat ?

[@fupabox]

Eric Cote no I don't...but here is one kzbin.info/www/bejne/Z3K8ZaKHl8aGf9E

[@Engineerboy100]

Excellent presentation, thank you, I think I'm gonna have to do this job, there is heat coming out on one vent and ac coming out of the other smh

[@mohamedamer8833]

Amazing video,thank you. Do they affect AC coolness if they are defective? I have a mono valve. Thanks again

[@fupabox]

yes.. it controls the amount of hot coolant coming into the passenger compartment, which can affect the a/c coldness

[@SaurierDNA]

But if your airco does not work, could this cleaning of the dualvalve kickstart the Airco cold air as well?

[@allkindsajunk568]

Hi, I have a 94 S420 and hot air is constantly blowing out from the side and front window vents. My core and valves look a little different.... would you recommend taking them apart and cleaning? Do you, or anyone else, know of any rebuild kits for the core+valves on my 94 s420. Thank you and GREAT VIDEO!!!!!!!!

[@fupabox]

if you can hear the click of the solenoid when you plug and unplug it ,they are generally ok...if not Pelicanparts should have the repair kit...it can't hurt to check it..I think there is a w140 duovalve video on youtube as well..I remember seeing it at one time

[@allkindsajunk568]

thank you!!

[@JGO749]

Allkindsa Junk So it worked for you AllKindsa Junk?

[@Thekingdavidreich]

Thanks friend clean it as you indicated in your video and now warm very well greetings

[@peterrafeiner9461]

Well done video and explanation. Thank you for posting !

[@JGO749]

Hey with this setup I see the connector has 3 connectors coming from 4. I took apart the duo valve unit from my 99 clk320. I never heard click sound so before i consider buying a replacement i want to be sure there is no problem with the connector. Can I use a normal live wire detector? (Looks like screwdriver with bulb in it and tip is + while wire coming from head/back of handle has a clip for -)

[@JGO749]

Btw i trully appreciate your time for the video and responses : ) I also have a ton of pics & and a separate additional question. And facts related to my context, a/c stopped working and i have heat coming from vents when climate control is off or on. Cooling fans and compressor does engage. I thought compressor would fail to engage if freon was low so is it an indicator my freon lvl is fine?

[@fupabox]

yes you can check for power at the connector. check the fuses as well under the hood..make sure they are all seated securely

[@fupabox]

Jerry Ortiz If I am correct the duovalve defaults to full heat with no power going to it..as you said the duovalve isn't clicking...sounds like a power problem..if the freon was low the compressor would stay off..the a/c is prob. working ,just in high temp as it does when defrosting the windshield...

[@JGO749]

***** Thx a lot for the replies =D So I checked the 3 connector ends which look like empty cylinder (female) connectors with circuit tester (screwdriver tip test + and end of wire -) and the bulb did not illuminate.. Hmm I hope the climate control is not affecting the connector integrity but would have no idea. All my fuses were okay. Not sure what else to do unless an easy bypass was possible. Would a bypass with a clamp work over the input for testing to get cold back?

[@fupabox]

Jerry Ortiz bypassing may work.. have you done the hvac diagnostic ? Mercedes w208 clk320 how to display climate control fault codes

[@patrick9761]

excellent ez fix 220e w124 thanks for the vid

[@Sparexxy]

What if I clean it out and nothing is broke and I still don’t have heat

[@marcosfabioealinegarcia3298]

Dear friend, I have a problem with c280 97 in the air, cold air in the center, and hot air on the sides, could you help me? Thank you, I live in Brazil

[@fupabox]

Your duovalve is likely stuck,clogged/dirty, or broken ..causing warm engine coolant to enter the heater core even though the temperature is set to cold

[@joeychanco]

Hi fupabox, im a newbie just got a w124 e320 1995. My a/c is blowing cold air in the center and hot in the right and left vents, under too. Is it possible the duovalve is clogged? is it not working? thank you .

[@fupabox]

It is possible.. does the center get warm when you turn off the a/c and turn it to heat

[@joeychanco]

yes it does get warm. my mechanical skills is very new:) is it better to replace it or try to clean up the clogged is its dirty. thanks

[@fupabox]

I would try to clean it first..it's free, and only takes a few minutes

[@joeychanco]

ok ill try to clean up this weekend. So it might be just the valves not working properly? hopefully it works thank you.

[@muttnaughton9223]

hello, what would you use to clean if they are dirty? q tip?

[@fupabox]

q-tips have a tendency to drop fluff , so I would use a small paintbrush

[@triponionut1540]

Well, I did unplugged but nothing...no warm water is passing... My duovalve is an expensive one because of my auxiliary heater system, and hard to find on SH spare parts. I will open again, and I will pull out that plungers, so the water can pass this duovalve. Thank you sir for your help!

[@JAZ.80]

Hi! Thanks for the tip! i looked under the dashboard on passenger side and after un-screwing 3 bolts it lead me to where the aircondition fan is. Godness,

[@nicholaselias8542]

I had an issue on my w221 where only side of the rear would get ac. It turned out to be this unit. It is revised in the w221's but same design principle. Nice video. I ended up just replacing mine. Yer right it is a bitch to reconnect the hoses. I had to use 3 hose clamps to clamp each hose or you lose a ton of coolant unhooking the hoses

[@Artificial24]

hello futabox, i've got an 1990 w124 230e and i've got the following problem: the ceter vents, the one on the right and the bottom ones on both sides blow just cold air. the only one blowing warm air is the vent on the left. could this problem be solved by cleaning the duovalve? what could also be possible? thanks a lot!

[@marcusfinanger1116]

Did u find solution?

[@tainchains]

Have you ever done an output shaft seal on 2000 w202?

[@fupabox]

not yet

[@1985safraz]

I have just come across another issue electric radiator cooling fan failure. is there any way I can wire and electric fan to the radiator my old one has had its says as well as the resistor I've checked the radiator fan switch the voltage stays at 7. Something something now j know thus much for sure when the temp reaches 80 degrees ecu is supposed to rein put power into 12 volts thus activating fan which it isn't I'm prepared to do the wiring just wanted an advice so perhaps u could email me or better yet a video to boost confidence is appreciated

[@fupabox]

***** The control for the radiator fan comes from the resistor unit inside the drivers side front wheel well. Any problem with the fan not coming on usually is a fault in that resistor unit

[@1985safraz]

Thanks you the man it eventually was the resistor now my engine is running cooler than before thanks for the advice now I better start on the interior now that the xxxking vandals had there way with my beauty I gotta find me a set of door cards and both rear window regulators and a good thorough clean of the carpets should do it

[@fritolay8668]

Do I need to drain something before I remove them?

[@fupabox]

Nope . Very little coolant will leak out

[@fritolay8668]

@@fupabox I just removed them. Now I got cool air on side vents. thanks

[@aldemos]

Awesome i have a w202 2000 merc c180! so ill now check if mines duo valve and see if it needed cleaning! (probably as the heating seems to be a bit slow) :D

[@unclejoe5541]

great info, except on my car there's no room to get your fingers to disconnect the electrical plug, or much room for anything else

[@fupabox]

yeah it's tight in there

[@TonyAMG43]

Making working on my W202 easy.

[@aleksandarjovanov2277]

I have problem with my mercedes w203 c200 cdi year 2001. When I put on a/c have cold air only on passenger side to driver side I have a hot air. What can be the problem? Thank you

[@fupabox]

try this kzbin.info/www/bejne/fmjPh4ypmLxopKc

[@skwiot86]

Where is duo valve located on w220 s320 cdi diesel? its uk spec car.

[@fupabox]

Kamil Skwiot the factory manual page ,,,workshop-manuals.com/mercedesbenz/s_500_(220.175)/v8-5.0l_(113.960)/heating_and_air_conditioning/auxiliary_water_pump/component_information/locations/coolant_circulation_pump_a31m1/

[@skwiot86]

That's s500 with petrol engine so it's different then mine. I need to find the duo valve on diesel.

[@fupabox]

Kamil Skwiot Yes unfortunately I don't have access to the w220 diesel repair manual...the one for the s500 is as close as I can get..I'm not extremely familiar with the w220.. If it is like the w211 it may be under the windshield cowl by the wiper motor..if you follow the coolant hoses from the engine back toward the firewall you should be able to find it

[@Thekingdavidreich]

Hi I have a Mercedes E320 98 , and the air is not heated , this valve is related to this problem

[@fupabox]

yes , the valve is the most common problem for no heat

[@Thekingdavidreich]

thanks for the quick response you 'll do the service that you indicate and inform you thanks again

[@GSX1400K2]

Nice video. Why are there 2 valves? One for the right side, one for the left? I have no cold air only on the right side on my car, is it possible that only one valve is sticking or blocked? In which position is the plunger letting hot coolant pass : when it is in up position our down position (rest position is???)? Thanks to anyone who would happen to know! Cheers

[@fupabox]

+GSX1400K2 I think the duo valve is for the dual zone climate system, and the monovalve is for the single zone system..I think.. the valve will move up to allow more coolant through.. I would assume rest position would be down because there would be no power to the valve to lift the plunger...you can also try the vent flap test to see if all the vents are working properly...the est is in the w208 playlist on my channel

[@GSX1400K2]

+fupabox Thanks for the answer. I took mine apart and found a lot of coolant in the upper part. Should this be? I may have a leak that allows the coolant to go to the upper part, the electrical part?

[@fupabox]

GSX1400K2 coolant shouldn't be getting up in there..there may be a rebuild kit for the seals

[@GSX1400K2]

+fupabox That's what I was thinking...I'll have to see if a rebuild kit can be found or just change the duo valve. Thank you for the feedback and for this video.

[@fupabox]

GSX1400K2 very welcome :)

[@jrnr6414]

Please help me..I just clean the valves but when I tested the clicking sound is very low..not like you valves in your video..maybe the valves are damaged? ....my air was blow air hot in drivers side and some cold in the other side..and then both are blowing hot...I just put freon and still hot. .

[@fupabox]

Jrn R you may need to check that the springs are back in properly...if they can't move up and down freely they will stick open

[@jrnr6414]

They Have a good play... :s .....before I close I just check that and them go down and up freely...I cleaned very nice and everything any suggestions ....please ...and by the ways nice video you have boss

[@fupabox]

Jrn R The only other thing I can suggest is to check the electrical connections and fuses

[@triponionut1540]

Hello sir. I have a problem with my duovalve from my '01 E-class. Is very similar with the one you have on your car. My duovalve is clicking when is on cold vent, but it seems like I don't have any heat in my car. I opened my duovalve and anything seems just fine, but again is no heat in my car.Is posibly not to open that plugers because of that springs? Any ideea? Can you help me please? Thx.

[@Squ33zeN9ne21]

I have a 1998 c 280 and when i drive and press the gas my center air conditioners stop blowing then come back on in like 3 to 5 mins. Could u tell me if thats normal or is something wrong

[@fupabox]

sounds like the vacuum change when the engine revs causes the vent valve (vacuum operated ) to revert to closed ..then comes back as vacuum returns with lower throttle opening. A vacuum leak somewhere in the system .

[@jegco20]

Hi there, bro. After going through diagnosis, the code that appeared was B1416, the circulation pump. So I got across your vid and did the step by step cleaning. However, the same code remained when I diagnosed it again and after I tried to delete it. It just comes back. I notice that the duovalve on my CLK 320 '97 is heating up but I can still touch it coz it doesn't burn really. But is it normal for the duovalve to heat up even when the car/engine is not running at all? Also, maybe you can help, these are the values I got from the sensors: 1- 30 2- 40 3 -23 4- 23 5- 67 6- 83 7- 12 8- 53 It appears that my evaporator temp sensor is faulty (#5) because it shows very high temp at degrees C. Are these two (sensor and circulation pump) connected or something that my compressor shuts off after a few minutes? Thanks friend.

[@fupabox]

jegco20 The circulation pump is a small fuel pump looking thing under the air filter, with 2 rubber rad hoses (about the size of the duo valve hoses) to check it turn the car off and keys out of ignition and press the "rest" button...this is for maintaining heat in the car interior in winter when the car is off and you run in to do some shopping etc. with the car off and rest pushed ( it should light up red) you should be able to feel the circulation pump working .''if it isn't it may be the cause of heat not coming out of the evaporator and basically being retained inside the hvac unit ..that would tell the compressor to shut off...so most likely the pump is faulty or has a bad connection or fuse

[@jegco20]

***** ok i got it, bro. thanks for the info. will check it out. and im doing something for my evap temp sensor too. :-)

[@abdallahd.1505]

well I unscrewed it but it refused to be taken apart it was so gummed up and the gasket was toasted so I bought a used one and replaced it and now im getting hotter air than before. it's a bit hard to work on but it can be done

[@fupabox]

+abdalla Dar Good job :)

[@cornelbotnariuc4636]

thnaks, it was very helpfull for me

[@atea4001]

My W202 aircond compressor didn't cut off. Check & cleaned interior temperature sensor. Also replaced AC evaporator sensor. But it doesn't solve my problem. Any idea to solve my issue. Thanks..

[@fupabox]

razali idris the a/c compressor won't turn off ? or the fan blower ? to turn off the compressor the EC button must be pushed. If the fan stays on, generally it is the blower regulator

[@atea4001]

Thanks for your fast response. My problem was auto cut off for compressor didn't function. Manual no problem (EC button ). Normally compressor should cut off once reached at certain temperature. But my car compressor keep running.

[@fupabox]

razali idris I wish I had some info on the compressor cycling..Ill see what I can find in my manuals

[@atea4001]

Please. really appreciate.

[@fupabox]

razali idris I called a Mercedes mechanic friend ..he said unless "EC" is pressed..the compressor will always run... I generally leave the EC button pushed unless it;s really hot outside, but I prefer fresh air to A/C

[@Passionate747]

Very excellent video my heat work very good thanks for doing this video.

[@Urxiel]

Hey Fupa, I tried your trick in disconnecting and connecting the wire to hear the magnetic thingy reacting. I didn't hear anything, I think its a fuse issue, any idea which fuses are responsible for powering the duo valve?

[@fupabox]

what year and model is your car ?

[@Urxiel]

Mercedes Benz 1999 W202.

[@fupabox]

Urxiel check fuse # 2 and 3 also check the wiring to the duovalve ..see if there is 12v getting to one of the wires (center one I think)

[@Urxiel]

You are correct, the center connector had an active electric current, so I removed the golden pins and the heater worked. So I'm going to need a duo valve. They're sold on ebay for about $30

[@fupabox]

excellent.. should be good after the new valve is installed

[@faisalaldaboubi4916]

Hi My w210 /99 has an ac problem.I'm unable to switch the air inside and outside. I always get the outside air with all bad smell from outside

[@fupabox]

The cabin air filter could be plugged, the recirc flap could be broken or blocked , or the vacuum line to the recirc. Flap could be leaking.

[@Joloke08]

Great Video I have an 89 E Class exactly the same DV as yours. I can hear my duo Valve inside the cabin though and its driving me mad :( Solenoids click as they should and my heat works as it should but surely I should on hear the clicking under the bonnet not inside the car :( Need a solution as the noise is quite literally driving me around the bend!

[@fupabox]

+Joloke08 unfortunately the only solution is to replace them.. they get noisier as they get old and rattle a bit.. I guess you cold wrap some insulation around the valves to keep the noise down. rockwool green sound insulation from a hardware store may work

[@Joloke08]

+fupabox Thank You for your reply, I have to say they don't seem noisy they seem pretty much like yours do but I would of thought its not normal to hear them operate inside the car? I live in the UK so our cars are RHD so In my case the duo valves are right in front of me so as you can imagine the sound is driving me nuts! I had thought of wrapping them in sticky sound deadening material but didn't know whether it would adhere because of the heat generated by the DV? Will follow this video and try and clean mine out ;) Only had the car 9 months but had the coolant changed out immediately in case it wasn't MB Fluid so those valves could be gunked up I guess ? Thanks for taking the time to reply :) Subscribed now :)

[@donkhalifa3422]

hello my car is w202 c280 it had no heat I cleaned these valve after that was good.So now its always blow hot air if I switch on air conditioner still hot .when I open engine aircon is running but theres no aircon inside only hot air comes out please help I'm stressed.

[@fupabox]

possibly the valve is now stuck open...plug and unplug it while the car is running and listen for the solenoids clicking ...if you hold your hand on the valve while unplugging it, you should feel the clicking as well

[@Mientras_Tanto]

Where is located in the ml430 w163?

[@alexle5026]

Mine were at cold on the passenger side, now is at heat but can't get it back to cool again.

[@tomaskinnunen4529]

thanks🙏