GMC Jimmy, S10, Blazer DIY How to Diagnose HVAC Mode Control - Vent - Defrost - Floor Selector

[@nogripes]

Replacement HVAC actuator on Amazon - amzn.to/2GCSjdR Replacement Blend Door Actuators on Amazon - amzn.to/2EiD8sH Blend Door Actuator Gear Rebuild Kit on Amazon - amzn.to/2N9IdpP

[@chrismongognia1016]

Which one of these is the upper vacuum with the yellow and brown? I need to replace mine but cant find where to get one.

[@fishingmojados1121]

@@chrismongognia1016 they are no longer available anymore

[@kevinpoupore742]

Thank you for posting this video. I just replaced my heater core and put everything back together (or so I thought). Selector wouldn't change into defrost. Turns out the vacuum line right next to your forgotten screw wasn't plugged in. Never would've caught it without this video.

[@redbear9943]

I was just about to buy a brand new heater core till I saw this. Thanks for the input

[@daveschidlmeier6425]

Before changing heater core radiator try backflushing ìt. I had very little heat at any setting on my 99 s10 blazer system. I pinched the inlet and output heater hoses with 2 pairs of needle nose vicegrips. I disconnected the hoses and installed 2 temporary 5 ft long hoses. I connected my garden hose to the outlet side, cracked the valve on and caught the discharges in a 5 gallon bucket. I reversed the flow a few times till the discharges were clean. Then blew air thru the core to remove the water. Then filled the core with antifreeze about 1 1/2 pints, removed temp hose, then reconnected the heater hoses. What a world of difference that made. Got good heat once again. I wouldn't change the core unless it leaking fluid into the cab.

[@gsprof9788]

Look behind glovebox door, look for the actuator on the right side of HVAC box that goes to a lever on top of HVAC box (not the recirculation actuator). disconnect the brown vacuum line to it and plug it. Now see if the other functions work. There is a vacuum line junction box there just below actuator that you can seperate and check vacuum on all lines from reservior to actuators. Also the Transfer Vacuum switch as mentioned in other posts don't worry about transfer fluid getting into HVAC lines remember the engine is sucking the lines towards the engine. BUT under the hood look for the vacuum reservoir tank inside the back of left front fender behind the antilock brake module. Follow the vacuum line from the engine to a small inline plastic check valve or filter (thats where you'll find evidence of oil from the transfer case) the vacuum lines tee's off to the tank, the HVAC, and the transfer case switch lines from that valve/filter. According to GM replace the reservoir and/or valve if your not holding vacuum with engine off. I'd replace check valve/filter first before replacing reservoir.

[@jpbuchanan25]

I checked and Followed the yellow line going towards the middle of the dash and found a hole

[@soldier4christsoldier4chri90]

What filter are you referring too. I have these same issues.

[@kylesmith7354]

Hey Mark, my 2000 Jimmy has the same issue and i figured out a temporary fix last night. That upper actuator hooks on the vent door lever. At the vent door lever i unhooked the spring that helps open the vent door. Now the actuator operates like it's supposed to without the spring tension. Fast, no cost, easy but not the correct way!

[@scarakus]

This is always the go to channel for blazers.

[@shanesmith831]

Where can I find part 2 of your fix with the blend door actuator? I have a 2003 gmc sonoma with same problem and wanted to know if I have to take out the dash to fix upper actuator on the driverside.

[@kolbpilot]

Gotta love youTube. Better than a technical library. Thanks for posting this. I learned even more. I'm slowly deciphering the mysteries of my '97 Blazer, having owned it for 3 years now. Really nothing to 'em, standard Detroit fare. My 2wd makes it even more simple. Why the old way direct cable vent door actuation couldn't be retained instead of this troublesome vacuum system is beyond me? Probably packaging advantages. Mine is stuck between defrost & footwell, probably not a bad combination. Will monitor for a while.

[@danhowe8145]

Remove the spring from the top actuator. You should be able to just push the spring up right off of the bracket that holds it. Worked for me on my 2002 Blazer

[@heyRolleen]

and scored 83 cents! After watching this video the SDIC (AKA my husband) is convinced that the vacuum line that runs the AC part has come off and he just went out the front door to attempt to fix it.... he added freon yesterday but it still only blows hot air.

[@hkr321hkr]

Thanks for the quick video! Just the way they should be! I heard a vac leak and now nothing is switching. I'm pulling in apart today. I'll be back to let you know! Thanks again

[@jamieclay007]

One silly mistake to look out for. My HVAC stopped working and it was just after I serviced the engine (replacing rotor/plugs). When I put the cowl back on, the damn vacuum lines got between the cowl and the firewall, pinching them off. So - there's something check first off. :) Thank you for your video though! It got me exploring the problems just the same.

[@jimmyhamm6041]

It's the actuator. I need to look into my 96 Sonoma this summer it only works blowing on high and it barley blows anything out the top dash vents . The defrost and floor work great.

[@gregwickersham1390]

Exact same on mine, 96 jimmy

[@jflow53569]

I have been having the same problem for over 6 months now. I have been waiting for a part 2 to this video for 5 months now. Are you going to do a second part to this video?

[@shelbymachine5218]

I had the same problem in my 2002 Blazer. I pulled the actuator forward and sure enough, my forward vents closed. I do notice a spring finger seen in the video on the lower actuator that seems to be out of place. I'll investigate that, but like the video, there is slop in the actuator, so that may get replaced.

[@Sconda75]

Thanks for the video. I just put an aftermarket radio in my vehicle. I pulled wires down through the dash and I believe I messed one of my vacuum lines up and now I hear a vacuum leak behind my radio .this video was extremely helpful. Thank you again

[@sybaker9573]

Hey Mark, do you have a part number for the blend door actuator you replaced. I have the same problem

[@steelhanded11]

Did you figure out it it was a vacuum line or the actuator??

[@allentig]

check the vacuum lines under the hood, that run over top of the brake booster. ... my 98 s10 was doing same thing, the vacuum lines from intake manifold, then over top the brake booster to the fender well were dry rotted and basically crumbling.

[@blakeslattman3405]

so after you replaced those lines, the HVAC modes worked?

[@allentig]

yes! wish i had got off my ass a few years earlier and did that...... drove with a foggy window for a long time, haha ..... yea man, it still works fine

[@joew9392]

I just fixed mine last week. They sure must have put cheap hoses in those S-10s. I just did the one coming from the intake, the small hose at the Tee and the one going to the fender. I have no idea where the one ends up that goes under the dash..

[@jimwilliams5349]

After checking all the items you show in the video, my 2003 ZR2 only blows air from the drivers side of the window defrost vent (when selector switch is in the defrost position) and still blows out the dash vents.....any ideas? I removed the spring on the actuator.......no change.

[@kylesmith7354]

I doubt it would be the 3 vacuum lines under the hood since you get vacuum to the actuators. I think you're on the right path with replacing that actuator that binds up.

[@fueledbyrage32]

I have a 1999 GMC Yukon and problem is similar. Air blows out of all vents (dash, floor, and defroster). Do you think it is my actuator? It is a different set up than the one in this video.

[@stevenjack23331]

Have the same issue on my 1999 Blazer LS. HVAC and actuator behind glovebox works fine. Floor/vent works also but vent wont shut off. I can feel it moving so I gotta tear out the counsel to change the vent HVAC. Great video and helped keep from taking it in to a shop lol.

[@stevenbrindisi4719]

I have an '02 Blazer, the vent is always on, floor and defrost will switch but sluggish to do so. I removed the panel below the ashtray and its the same as in this video. I can pull on the vent actuator slowly outwards to get it to lock closed until I shut the blazer off when it loses vacuum. I rebuilt the hvac mode switch where it was hissing thinking that was where the problem was but no, it's the vent actuator gone bad. I found small traces of probably transmission fluid (from what I read) in the yellow line going to that actuator as well as in the mode switch. 4x4 works, everything else works on the vacuum except the vent actuator and I can't find a new one anywhere. AutoZone looks at me like I'm stupid when I ask them if they have one. A quick Google search comes up with a blend door actuator which is not the actuator in question. Where can you get this part?

[@613scorpio]

I replaced my stereo in my 02 S10 because the factory one was spitting out cds & constantly saying ERR. When I looked down just below where the radio sits I saw a puddle of oil?? I looked & smelled like oil. I popped out the heater control panel thing & the vent selector knob was leaking it from the back. There's what I think is oil all over the inside of the dash in that area. I finally found where the PCV Valve went & changed that. Not sure if that's a fix for the prob but I was wondering if I had to replace the part on the back of the vent selector. If so, wth is it called & if that's not the prob, any ideas what else it could be? I also have to replace the 4WD actuator wire. Sometimes it doesn't want to fully engage when I hit the button. Any suggestions, I appreciate!!

[@stevenbrindisi4719]

It's not your 4x4 wire, it's the actuator. Oil is very bad for your vacuum system. The cause of this problem is that a seal breaks between your transmission and transfer case, dumping transmission fluid in the transfer case, the vacuum actuated switch on the transfer case allows that fluid in, gets sucked up in the vacuum lines and gets distributed to all of the actuators, 4x4, vent, floor, defrost, heater blend door, and mode switch on the dash. It's a nightmare. I traded my Blazer in a few days ago because it was more than what I could take on. It's a common problem in these vehicles too...wish Chevy could have done something about it. I guess they did when it got discontinued.

[@613scorpio]

Steven Brindisi UGH!!! I love my truck!! It only has 86,500 miles on it & I wanna keep it till it dies seeing how I don't want to pay a ton of money for a new or used one. It idles like I'm about to drag race too!! That's been happenin for a few yrs too. I read that has to do w/a vacuum leak too. I swear I have the absolute worst luck. I plan on replacing the 4WD actuator & the wire that goes to it because the wire looks like if I blow on it, it'll crumble. Any idea how to find or where to look for this broken seal? I mean a whole sheet of a crappy paper towel was sopping wet over night when I had the heater control panel out. Plus my EXmechanic had me replace that actuator that moves the vent, feet, etc. TWICE. Told me it was a dealer part so I paid outta my ass for it TWICE & that clearly isn't the prob for the 2nd time because it decides to change to whatever it wants after a while. It will go over but after 10 mins or so it does whatever. So any help or suggestion I'd appreciate. Espec w/the idle. Thanks!

[@eastmonroeavenue]

It was brought to my attention that a plugged PCV valve causes pressure to buildup in the case. Old seals are the weakest link, rear main seal leakage is also common.

[@ChuckWood]

I had the same problem, the diaphragm closest to where the driver sits was torn. Looking for a replacement now.

[@miketoth613]

My 2002 Blazer always blows air out of the dash vents.I was wondering if a bad vent actuator could cause alot of outside noise?

[@amused2deth]

Where does the vacuum line come in to move these? I'm having the same problem but I think mine is more of a vacuum leak somewhere. Plus mu blower speed controls works on and off.. Sometime all speeds are a low speed and somestimes its normal? Any suggestions? I want o fix the vacuum leak first though... Thanks!!

[@stevemadak6255]

My problem was with the vacuum lines in the engine compartment. 7/32" and 5/32" lines. The old ones got hit with some engine degreaser and they collapsed. Thanks for video.

[@KeithFox]

Steve Madak Me too. '97 blazer vacuum lines at the T, driver side under the hood. Vac lines were rotten to shit. Need to replace those. Hopefully this vacuum leak has something to do also with the bog down power loss. I really don't want to replace my fuel pump. Is the vacuum line only for the defroster flaps or does it also affect engine performance? Trying to narrow my fuel issue down to either dirty MAF or fuel pump issue.

[@KeithFox]

Yeah I had to fix that honeycomb converter issue too. Took the pieces out. It usually happens when it's lower on gas and trying to accelerate moderately-heavy. The temp solution is ease off the throttle, and get to the nearest gas station. I really do need to change fuel filters, never done it and had the vehicle for 5 yrs. I can hear the fuel pump whining sound too so that can't be good. I suspect the pump is going out since it appears to be common. The gauge is in and out, appears to be a resistor issue for the gauge. I came across some info about a dirty MAF sensor, so while it was running I unplugged it, notice a blade of grass in the plug socket so I blew that out, reconnected it, and have not had any major issues since. Really strange, but the check engine light went off after resetting it and hasn't come on since, also been running okay this past week. I really should change the plugs in it too, sounds like the one may possibly be misfiring intermittently.

[@KeithFox]

Also I found out the vaccuum line that is broken is for controlling the heater/fan so I can't move the position of the blower is all that affects which is nothing major at the moment.

[@MegaDave1962]

My 97 gmc Jimmy airflow always goes to To defrost during acceleration, I've replaced the vacuum ball and vacuum hoses, I'm thinking a leak in the cab? What do you think,

[@richv7095]

How do you replace the valve vent lever. I broke it replacing the actuator. I can't get the old on off to put the new one on. Thank you.

[@TheHowToCorrectly]

Any idea of what the blend door actuator does on the passager side behide the glove box? The one with the vacuum hose. I noticed the at the end metal thing that goes in and out is broken that’s connected to a white plastic piece

[@Dizzledude2012]

Thank you! I wish more people were this informative!

[@nancyhoward769]

i have a 2003 chevy s10 xtreme . i have been having problems with the a/c . one it doesn't blow very hard at all . two if it i come to a red light it starts blowing hot air and not cold . any solutions to what could be wrong with this . any solutions would be greatly appreciated.thanks

[@newellbutch]

This may be whats wrong with my 2000 ZR2. No matter what the floor and windshield vents are doing, I always have air coming out of the vents. In the case of complete vacuum failure, default air flow is supposed to be diverted to the windshield and my truck is not doing that. I'll have to check this out. Thanks a lot this really was helpful.

[@jayryan7473]

So just totally ignore the essential vacuum lines under the hood? It's kind of like checking your spark plug wires first to see if they're hooked up before replacing an entire engine LOL. Check the simple things first.

[@Drago0900]

Well to be fair in this case with no vacuum it would do absolutely nothing. Since it was half working it should mean its got vacuum.

[@ShawnEdgar-rv6fp]

@@Drago0900so mine is not working at all. So I went under the hood and I found oil in a line that that comes from The intake and splits off into the PVC valve. The line that runs to the canister at all in it so does that mean that little valve that is right there bad?

[@x--WarHawk--x]

Very helpful video. Were you able to figure out if it was that actuator you commented on or was it the vacuum lines? I don't have any footwell airflow right now...so I'm inclined to believe you have hit the exact nail for what my problem is.

[@mooseman175]

Hey Mark, loved your vid and was wondering how it all turned out and what you had to do to finish repair. I have the same problem with my 2000 blazer. No air blows out the foot wells. Did you do a vacuum test and did you replace the actuator? Thanks Mark

[@Blueknight1960]

I just acquired a 98 gmc jimmy 4x4 that's doing the same thing but, that's at the bottom of the list right now. Have to get it ready for a state inspection and emissions test. It also needs an a/c compressor. Luckily I can do the work myself.

[@MissRodrigu3z]

Quick question, I have a '04 Blazer and the inside of your car from the vid looks exactly like mine. did u ever experience hot air (w/ faint exhaust smell) coming out from over the gas pedal? and bad car vibration (accelerated speeds & idle)? would really appreciate any insight.

[@WeThePeople-hk2rb]

Also, great video, to you didn't go over other possible things that can be going wrong in that area and also a good look at all the vacuum hoses that are connected to the ventilation system. can't seem to find any videos like this. I'm just kinda learning about auto repair and this is my first s10 and I just got it. it won't switch back and forth from floor vent to defrost vent. it just stays in one mode basically. 80% front vent / 10% floor / 10 defrost

[@mikegrassman4773]

that's my problem. What did you find?

[@WeThePeople-hk2rb]

@@mikegrassman4773 I don't remember what I did, I ended up selling that truck like 5 years ago

[@1985kenworth1]

I had my heater core replaced and i get heat from defrost windshield and heat from footwells but cool air from the dash vents ?Do you have any idea why ...never had this before.I had total heat from everywhere before the heater core was replaced

[@peterbaruxis2511]

Did you get that problem fixed?

[@1985kenworth1]

@@peterbaruxis2511 No ...its still not blowing heat as hot as it was before the heater core replacement ..Since this post the engine was rebuilt by a reputable engine place I have been dealing with including new head gasket ..The rad is new and I still cannot figure out why the air blowing is not hot as it should be.This is my 3rd jimmy and I owned and never had this problem with heat from the others .It's frustrating to say the least.I think the garage that replaced the heater core either broke something or did not put it back together properly .Unfortunately I have no recourse because they went out of business .Afraid to take it anywhere else in case they mess it up even worse.If you have any suggestions to look for it would be greatly appreciated ..I have some mechanical background .I do my own brakes and replaced the blower motor .Not savvy with how the heating system works .Thank you for asking

[@peterbaruxis2511]

@@1985kenworth1 This video seemed possibly helpful- I have similar trouble. I'm going to look for those actuators and vacum lines, also one commentor said look for an actuator behind the glove compartment. I do a lot of my own work- I'm not a professional- a friend (ASE Certified auto tech) helped me replace my heater core, 2000 Blazer 4.3L V6, very similar to your's I think. My "Haynes Repair Manual" say's the dashboard needs to be completely removed. If I remember correctly that's after removing the two front seats, etc and a lot of wiring.... It's all very do-able but many hours, then the heater core is right there to change as easy as changing your socks. Against my objections we did it the way many or most "professionals" would by "only" tilting down the dashboard without complete removal then squeezing out the old core and squeezing in the new one. I know for a fact that per procedure one particular bolt that gets removed MUST go back in the original location to avoid interference with a diverter door (this bolt is probably shorter than other similar bolts that were removed) & IDK if mine went back together correctly. I get hot air coming in in the summer and cold air in the winter mixing with what should be coming from the heater. Check the heater core hoses right at the firewall at operating temperature- if they're hot the air blowing into the cabin should be hot. Maybe (like mine I think) it's a diverter door issue from one cause or another. Good luck ! I'm gonna try to get mine working right and I'd like to hear if you get yours going.

[@1985kenworth1]

@@peterbaruxis2511 I did check both heater core hoses and both are hot as they should be ..I am getting heat blowing in the cabin but also cool to cold air blowing in from somewhere especially when it's at the freezing temp or colder ..its almost as of the ac and heat is on together.Again never had this problem before until the heater core was replaced ..it blew hot in winter and cold ac in the summer .Reading your reply ic old very well be an actuator door or something you mentioned about a small bolt interfering with a door ..Its really annoying because all my Jimmy's I owned never had this problem after the heater core was replaced and I replaced the core in both I had prior to this one .I am going to look further into it because I am positive it's something that the garage broke or forgot to do or was not paying attention when they did the repair .I appreciate your input and will keep you updated on the progress and hope you get yours sorted out also .

[@peterbaruxis2511]

@@1985kenworth1 👍

[@fatimadnoor7563]

Hi. Referring to a 2001 GMC Jimmy 2WD. HAVING THE SAME PROBLEM. But None of the Colored Lines have vacuum in it. . What could be the problem?

[@tkong35]

Was this a fix for the air constantly blowing non stop ?? Heat

[@soylentgreen2065]

i have a 98 Buick Lesabre and this is my issue: the AC is on and i have the vent control on the dash/mid/center vents so it blows straight out towards me. after i drive for about 20 minutes or so, the air flow changes to the defroster vent. ive noticed that sometimes i hit a bump in the road and the air will go back to the center vents but only briefly before it diverts back to the defroster/windshield vent. i understand that for safety reasons if the car loses vacuum the default vent is to the windshield to keep it clear for safe vision/driving. i used to own a 93 buick lesabre and it had the exact same issue. please, if you have ever had this issue and resolved it, let me know how. thanks!

[@jamesberns9129]

hi mark I was wondering where would I get the actuators cause my 2003 chevy blazer is doing the same thing. If you could get back to me it would be helpful thanks

[@marinehm]

I hear hissing noise when it's on the defrost position. Could there be a hose leak or disconnected? Maybe a bad selector switch?

[@francescosuarez]

Hello so my cold and hot know turns but it's only on cold it won't change to hot, what can cause this the actuator ??

[@awakenedtotruth8419]

Does the 2WD use this same actuator?

[@deathmetalbobii7433]

hello got a problem with my jimmy 1996 truck model.....why my air conditioning pump will then stop run then stop run then stop...before it was okay then suddenly its just run like that..i check it and i here a clicking like in a relay..can you please help me diagnose it!!

[@ken48827]

You are probably low on Freon. I have to add about a can every year. It is easy to do.

[@bonecrusher7297]

I need help with mine.... Sometimes it just stop blowing air.....doesn't matter if it's cold or hot air or day or night.....one day it could work and next no ANY TIPS??

[@TeDuaMalakie]

Thanks. What else American cars have to depend on engine vacuum to open and close air vents and flows?? I know gm with series S have this already. I think its awkward and scary way...

[@OMGWTFLOLSMH]

They're poorly designed junk wagons. I know, I have one. Low miles, low usage, garage kept and multiple things like this have failed on it. Cheap crap using cheap materials and designed by chimp brains.

[@davidwebb2467]

OK, how do I know wether or not it is an actuator or the dashboard switch itself, or both? My dashboard switch for the fan only works on 4, and the H/C middle switch doesn't seem to do anything any more? I'd guess the dash switch unit?

[@wesleydavidson558]

Did you get this figured out?

[@jamesellia6102]

What happened to all the square body s10? No body work on them anymore

[@myfun01]

I to have the same problem but it's not what you saw in the video the problem lies behind the Ashtree remove the ashtray assembly there you will find all the vacuum lines into one module to the right you'll see all the wire connection hold for a few seconds and you will see that the heat will function it worked for me hope it works for you good luck

[@myfun01]

I guess after time the heat wiggles everything loose

[@daleficklin1607]

Mark, A buddy of mine is having the same problem, air from vent only. He has exposed the actuator but he can not remove it. How is this done? Has anyone found another answer to the problem? Thanks

[@davidmoore6392]

Thanks, great video. I have the exact same problem. Did you find the solution?

[@MAGWolf]

Is this the same as a 96 S10 Blazer?

[@andrewfarrant198]

I have a situation where everything is turned off & still have air coming through the ac vents only when driving. Turn the temp control to hot & gets slightly warm is all. Got any idea which actuator I should be looking at.

[@williameldridge9382]

Air will ALWAYS come through the vents, even when turned "off". Unless you hear an actual blower motor running, it's just the ambient air coming into your vehicle. There's nothing you can do to stop this, it's a safety feature as air-sealing the cab of your vehicle would be a terrible idea.

[@allencrabb1180]

Just an update...I ordered the one above part # 52494116, got it off eBay genuine AC Delco part. I didn't have to remove my console, there is enough give in the bottom panel to slide it sideways for access. I used a mirror to be able to see up in there. The new one just clips in place. Fixed it!!!! The old one obviously has a hole in it because if I blow in one side air comes out the other side. When I would be under had acceleration or climbing hills it would switch from floor to vents and from recirc to fresh and back again. I watched it after turning the engine off and it didn't move on its own which means this was the source of my vacuum leak. Took less than an hour!

[@allencrabb1180]

***** Not bad at all! The mirror helped tremendously, that way I didn't have to stand on my head upside down trying to see. Grab the actuator itself and pull towards the door, it just popped off its bracket, disconnect the two vacuum lines, then disconnect the spring clip from the arm. Install was easier than removal. Wish I could have made a video but don't have that capability right ow.

[@HauntedPurpose]

***** sorry to hear about your ribs. Hope you're better. If you do make a video on how to fix this or replace it that would be awesome. Mine is doing the same thing.

[@jerryhebel5404]

HauntedPurpose

[@duggandh]

Is this vehicle still on the road? Nov 2020

[@jamesellia6102]

I want to know what's the best way to replace the blower control switch on a 1987 and 1988 s10 not a 2003

[@stevenkmckendallsr1169]

Would you please kindly do a video on replacing a 1996 GMC Jimmy SLE (4 door), driver's door latch. Thank you.

[@Skyhawks1979]

Great video Mark. I have the exact same symptoms as you do on my 2002 crew cab. Are both actuators the same part number? They are cheap enough I'd like to have them on hand before I dig into this.

[@matthewgray3032]

I see the red and blue wire if I disconnected the red wire would the heat stop Thanks?

[@jingles373]

Nice post! Is there a part 2? I have the same issue with my s10.

[@aliasprojects6214]

It would be almost identical in the S-10 (around the same year.)

[@pj8401]

This was a great post / video. I know this is an older post from you, but I'm currently dealing with the same issue with my 04 ZR2 (No heat or air flow to the floor). My question is of the 2 actuators you previewed, the first one (the lower actuator with red & blue lines). Is it suppose to "Wobble" when opening & closing? On your video (and on my ZR2), it seams to bind up while its opening and closing. I unhooked the actuator and "free handed" the arm and it doesn't feel like its attached to anything inside. Just kinda flops around with nothing attached. Do you suppose that means the door is broke off inside ?

[@Alexweav79]

P J Would like to know this as well as mine does the same thing

[@WeThePeople-hk2rb]

I have a 4x4 2001 s10 and the problem I'm having is the air won't change from vent to floor all the way. I can tell it is trying to change, and it does change a little but no matter what I do the air always comes out of the front vent mostly. I've changed a couple vacuum lines but I haven't changed the ones over the engine or the one going to the back of the controller. Also I can't figure out what the part number is or what the part is called in behind the vent itself. the little manual flap door that the front vents have. Anybody know what I'm talking about?

[@BowtieForLife420]

Check the 3 vaccum lines under the hood on the drivers side by the fire wall.

[@eduardosotelo6940]

No air comes out I changed the blower motor on my 01 Chevrolet blazer I checked fuses too and there good can someone help please

[@jflow53569]

I am having the same problem with my hvac system. Are you healed enough to finish a part two? Can't wait to fix my hvac problems.

[@rockband144]

***** So whats this magic spring and where is it located?

[@prankmonkey650]

I didn't get off as easy. Needed a new blower motor. But thanks for giving me an idea to look at

[@lockdupz]

Will this work for a 98 bravada ( oldsmobile)

[@singing008]

Were you able to get it fixed? What was the problem? My brother just gave me his '01 Chevy Blazer, and my feet have been freezing with no heat to them. Thanks for posting this...I'm just a girl with a set of tools my father gave me, so this is helpful!

[@lindapaivarinta9976]

P/N for the mode valve actuator is 52470773 but is discontinued. Looking for one also.

[@1dirtovalracer]

hi Mark, good video just have a quick question maybe you can answer it. I have a 2001 S10 Blazer with climate control and I have a heat issue with how much heat gets blended with the cold air in the vehicle . if I turn my thermostat knob all the way up to full I get full heat if I turn it down to read somewhere around 70 to75 degrees it doesn't seem like it is at that temperature. What could cause that issue and how can I fix it? right now my current workaround is that the heat is all the way up and I open the window. thanks and keep up the good work.

[@genarator8989]

hi, i have in my 97 tahoe some kind of a rectangular ring that should be attached somewhere to the actuator on the driver's side, this ring is what controls the air comes from front vents bottom vents, do you know where should i attach this ring?

[@genarator8989]

the rectangular ring is about 3cm x 2cm

[@99ramairgt]

The issue I’m having is that I have a constant vacuum leak at the switch itself, where you switch where the air comes out of. It’s currently only coming from the dash vents and won’t change. Now when I step on the gas the you can’t hear the leak, but once you let off the gas it’s back. I think it’s the red line. It’s constantly pulling vacuum. I replaced the switch itself, and it fixed the issue for a short while, but the leak is back. Helpppppp lol

[@bryantb3391]

Ive got no footwell what do u suppose it is?

[@matthewgray3032]

kinda,the heaters not kicken off,when the Ac is on the Ac blows along side the heat,I have a S10 2003,My Dad thinks its the Switch on the Console,During the winter I have to disconnect the Ac to have my heater working,so I was wondering what can I do?

[@soylentgreen2065]

Matthew Gray when i was trying to diagnose a vacuum issue i found a white plastic arm that controls/ diverts hot air. the arm was behind the glove box on my 98 lesabre. if i push the arm in, i get AC air to all my vents(which is the correct operation), just as i should. if the arm has backed out of the black plastic box it goes into, or i pull it out, i get hot air from some of the vents and AC from others. one end of the arm is connected to a long screw/or rod that goes into the vent box, and the other end is connected to an accuator arm near where the vacuum hoses are clustered behing the glove box. (the hoses are clustered inside a black plastic box but if you follow the hoses to their source, it will lead you to that box). if either end of the arm comes loose, the metal rod is forced out of the box and i get cold air (this is assuming the AC is on) out of some vents and hot air out of the others. i hope this helps someone.

[@matthewgray3032]

Ok so here's what I did,I added Cold water to my antifreeze port,after playing with my dials seeing about which dials provides the most cold air without blowing heat I seen that Dial 2 on High keeps my truck cool without heat blowing out,it really maybe a electrical problem,but this worked for me.

[@suzieq8379]

first of all I would like to know how to get in a position to get the those bolts I been all day just taking that one piece off LOL , rough , thanks for the video I need to put my record on cause I cant change the heater and watch to.. did you have to have all those parts or did you just replace it all Id rather not have to do them all LOL great video

[@DirtManDan]

links are for the blend door. not the actuator.... put up the right links if your gonna do affiliate programs......

[@prankmonkey650]

Working a problem with my 1999 Chevy s-10. Replaced the resister last year, problem continues. When it's raining or cold intermittently the fan blower will not work on any speed or setting. 15-30 minutes of driving and it will start working gonna check this. Thanks!

[@atfigure]

+prankmonkey650 I hve the same problem with my 95 s10, replaced all vacuum lines from the engine to the transfer case, now i know it has to be in my dash. was curious if you found your solution and what you needed to do

[@prankmonkey650]

+atfigure yeah needed a new blower motor and resister. I don't know how it was figured out, took it to my friends shop.

[@twistedman8]

prankmonkey650 any results on this issue. Mine Is the same way

[@allencrabb1180]

Hey Mark, Love your videos! I have an 01 Jimmy 4x4 and you have saved me a ton of money so far...my vents are constantly blowing too, but so is the footwell. I replaced the controller with a brand new AC/Delco unit since I found oil in my lines last year (swapped the switch on the xfer case thanks to your vid). I watch under dash and that same one as yours isn't moving at all. I checked It has vacuum when I move the selector, but it doesn't pull back. If I pull it back I have proper flow. But it pulls itself forward towards the firewall. Do you know the part number for that one?

[@martymcfly3986]

thanks for all the work put intit

[@Lake387]

mine does work at all, I used to work last week. but I get nothing at all on all selectors, it used to blow hot air, not its not blowing at all

[@mikekiefer6462]

I know the vacuum leak is under the hood for my problem. There is a T connection by brake booster. 2 of the 3 hoses have been replaced the 3rd I can't see where it goes too. 1 goes to PVC 2nd about inch and the 3rd I can't see where it goes. Does anybody know where it goes too?

[@joew9392]

One goes to the fender mounted vacuum reservoir and the other goes under the dash to the heater control I would imagine. I haven't replaced that dash hose on mine as it wasn't rotted.

[@EMurder1980]

Damn i was hoping this was the same problem as mine, my blend control won't work neither will my rear defog

[@brianboland7598]

On the 1996 gmc jimmy the actuator is under the dash behind the glovebox. we had to cut out the left rear corner of the glovebox and got it switched out. by the skin of our teeth. the only other option was to go straight down through the top of the dash. the back of the glovebox will not come out. if you have this model this is the best way to go. Don't give up wee!ll live to fight another day!!!

[@suzieq8379]

so was there a part 2

[@Barnekkid]

No part two?

[@pspgamerserjio]

So how do you fix it

[@philmanwarren3666]

hey mark is your dash lights work or no

[@Outdoorpizzaoven]

After taking the screws out I can't get the actuator out. It's driving me insane

[@daleficklin1607]

Did you get the actuator out? Having the same problem. Did this cure the problem?

[@Outdoorpizzaoven]

Dale Ficklin I got it out. it took a while and with the small space I tore my hand up but yes it worked

[@derrickbrasel181]

My ac goes to the foot vents when I press the gas an go over like 30 mph

[@boomernyob4930]

So it seems your problem of being stuck in vent mode was due to the actuator and not vacuum lines full of fluid due to the transfer case vacuum switch correct? I ask because I just bought a 2002 S10 the other day. I know it's stuck in vent mode but, I have been working 12 hour days since I got it and haven't had a chance to begin diagnosis. All I've been able to do is internet research. That's how I found this video. I hope to look into this in the next couple of days. Thanks for the videos.

[@zeuscarrillo7069]

*****

[@boomernyob4930]

The fix for me was to replace the vacuum switch in the dash that selects which mode you want. Floor,defrost, vent, etc

[@nate12281]

@@boomernyob4930 could you give me a link to the vaccum switch your talking about ? or is it called the HVAC actuator ?

[@boomernyob4930]

This is what you're looking for. Old and new part numbers are there. www.s-10crewcab.net/og1/modinfo/stockspecs/tcswitch/tcswitch.html Here's another article on it.

[@boomernyob4930]

That's the transfer case vacuum switch. In my case, I had a hissing from the dash. I replaced the switch that the vent selector knob in the dash is connected to. The one that selects floor,dash, defrost etc. and has colored vacuum lines hooked to it. I found a good one in the junkyard. So in summary, I replaced the switch inside the cab that I just mentioned AND I replaced the switch that goes into the transfer case in which I linked you to in a previous post. I'm not sure what your symptoms are. I'll be glad to provide any info I can to help you.

[@sblrealtor]

Awesome video-thanks so much

[@kingtkuehn]

Thanks! The Living God was here.

[@evelynvictorymatheny9047]

great sources! thanks so very much, I will use to check/diagnose mine.

[@ctg8563]

Hey I need help woth my heat

[@elkayezs8wslkwaterfountain826]

Not blowing hot?

[@gaxm99999]

I just put in a new battery and it fixed my no heat problem

[@lawrencerasmus]

Old cars would just have a mechanical lever. Wish it was 1950 again🤔

[@recentlychanged]

You don't have to go back that far. I had an early 90's Isuzu pickup with lever/cable HVAC controls. Never had a moments problem with them, and I had that truck for 27 years - until a crack developed in the block. Now I have a '99 Blazer that I can't even get the HVAC parts for - let alone actually fix the HVAC.

[@haxxord240]

Yea my wife is getting after me... When are you going to fix the Truck vents???? i am like i dono ill have to check KZbin lol... I am guessing ill need to learn how to replace the Actuators?