Coolant Fan Switch Testing WITHOUT Removing From The Vehicle | How To Bypass Radiator Fan Switch

This is how you can test a radiator or coolant fan switch without removing the sensor from the vehicle. This will also show how you can bypass the switch entirely and turn on the cooling fans instantly.
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• Cooling System
The coolant fan switch is sometimes referred as the following:
Radiator fan switch, engine cooling fan switch, fan thermostat temperature switch, thermo switch, thermo fan switch, fan control switch, coolant fan switch, thermostat temperature switch and water temperature switch.
Note:
Any attempt to repair automotive parts and/or systems carries risk of personal injury. Always adhere and follow safe practices when working on vehicles. Such as, safety glasses, jack stands, no loose clothing, etc. No guarantee or warranty is implied. Use the information in this video at your own risk. Carsntoys is a member of the Amazon Influencer Program.
Publication, reproduction or distribution of this film is strictly prohibited.
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[@4WinterTires-uv1mr]

Straight to the point. After browsing 30 videos finally found this useful video!! Thank you!

[@gregbiegel6468]

Great job! Excellent filming, and valuable troubleshooting advice. Thanks so much

[@dewholdingsllc1050]

Always best to do some testing of electrical connections and relay and fuses before throwing parts at the problem

[@skismosis]

i appreciate your knowledge my friend, as i own a daily driver honda accord 2005 EXL with 206,000 + miles that runs and drives like a ,new car , i have had to have a new water pump, pulleys and belt kit installed at 206,000 that was pricey as i did not want to tackle that job myself, i did take it to an ASE certified mechanic, keep up the great video's and thank you for your time.

[@CarsNToys]

Thank you. I appreciate the comment. I had an '03 Accord and it was arguably the most reliable vehicle I've ever owned. Cheers.

[@gabrielseaff487]

Excellent video and information. Thank you for sharing such a good knowledge 👍👍👍

[@DonBMW]

Great diagnosis and explanation. Having same issue with my 97 BMW. Same concept, same idea but have a low and high speed setting. Will bypass today to test the fans, but most pretty certain its the switch that has gone bad.

[@jerryibarra7958]

Great video! For those that have 98 - 02 honda accord. They have 2 switches. Both are located at the end of the radiator hoses on top of the motor, not the radiator itself

[@CarsNToys]

Thanks for the info! Cheers

[@HUMANOID6969]

Yeah I got a 99 accord ex and the fan switch is above my thermostat housing and the coolant temp switch is on the engine block below the distributor cap very odd places

[@thomastownsend259]

Superb video ! Well explained and much appreciated. DIY guys need people like you to help get things done . Thanks again.

[@billsmith4903]

Thank you for sharing Helped a lot

[@AimGobalWorldBibleSchool]

Thanks man...Funtastic!...Good job...

[@SuperSatturno]

Thanks, you really made my test quickly easy !!!!!👍😃👍

[@mohammadbenattia9102]

clear, neat ,straight forward problem trouble shooting, cheers

[@javierramirez691]

Thank you for the information.

[@hectorherbert6585]

I decided to bypass the systems and not wait for the ECU to receive that signal and start those cooling fans..I installed a switch and whenever I know the temp is rising (stuck in traffic or whatever) I just switch on those fans myself..it was not difficult to find the electrical 'montage' ..also my car a 2002 Volvo V40 was swapped with the V70 5 cyl turbo motor and jeez it gets hot in that bay..so I changed both (stock) fans for high power (CFM) new fans and now it's really 'moving' in there.!!..the heat sensor installed at the hottest point in the engine bay coupled with an extra temp gauge on the dash shows excellent results on extracting that hot air ,there is also lower temp thermostat you can change (95°C to 87°C)..but being able to control those cooling fans from the dash is for me the best way..keep that bay cool & ventilated..!!(The true success of any build or engine swap for your dream daily is all around 'heat management' & cooling)..Chip Foose.

[@zeez4178]

Great idea 🍀🤙🇬🇧

[@manuelacosta9182]

Thanks man!!!! I love you.

[@jackyphotos]

great video, on the other hand, can I just install a switch between the two switch wires , so that I can turn on the fan as I wish or let the fan on during high temp.? thank much

[@emmanuelhabte4491]

Thank you 🙏

[@Project.Mugen23]

Can I just say, the state of that engine bay and f20c is beautifully clean. I love the look of that enginee

[@willfulltruth9720]

I love your workbench it’s identical to mine but much cleaner newer and Jen sized

[@rachidkiwi5798]

Thank you

[@nickg2431]

FAN-tastic.was wondering how to test my motorcycle fan-YOU ARE GREAT!

[@yandinakathleenkhan8596]

Hi had a voxy 3zr engine fans not working even if you take out the sensor still not on. Put with scanner and on from scanner still not working, change fan motors as well. Fuse and relay already check are ok.... what you think might cause the problem please?

[@manuelagonzalezjr3451]

wow dude that's crazy because nine times out of 10 a lot of people wouldn't be thinking about that particular thing and because you went through it you found out that it was actually the sensor to your radiator and why your fans was not igniting I have a similar situation but my fans won't ignite the way that they're supposed to and the sensor seems to be working fine however mines is not digital like your odometer is so the heat to the car is right between the middle and a little less off the candlestick please so thank you again for giving me that idea to check it and also to check out my fans as well

[@TyroneMaye]

that quick bypass trick there would that also be viable to use say if your actual fan stopped circulating as you described. Now would a person be able to rig a set of wires as you did with the pin probes and got the fan to immediately come on. Without it running constantly while operating the vehicle ? meaning could it be set up to operate like a amp can be stilled used if fuse blew and you wrap a small amount of wire around the fuse and stick it back into the fuse location and it then returns power where it had previously blown leaving no power ? can radiator fans be done like that so they work but not work running constant?

[@SaleemKhan-ru5tc]

Excellent sir

[@samisulaiman7967]

thanks I have a Suburban 2012 and I want to make both fans works on high speed all time what I have to do should I remove only the black wire from radiator sensor .

[@jamesmonroe6]

Thanks

[@juantalavera2208]

Hello, so mines is a 3 wired connections how would I know which 2 should I used to do the test?

[@user-lr1cq8fk3i]

Very good video the one I am looking for well done one more problem is I change 3 cooling fan already they come with switch and I am having same problem over and over I change tempeture engine sensor same pb it’s driving me crazzy it turn on in low speed and at 210 and then stops goes 220 still off the power goes in fan but it’s not kicking at 210 or 220 it’s not kicking hight speed at all anyone any idea thx

[@josemagana2320]

My switch keeps going bad. After a week or 2 the sensor dies out and the fans won’t spin. I keep buying new ones and same issue, they only last 2 weeks tops. Wiring is good relay is good. Any idea what might cause my sensors to keep dying?

[@tedlahm5740]

what was the answer? not OEM parts?

[@dandahermitseals5582]

Thanks. I have an 87 Comanche 4.0 auto

[@sohanchari3973]

hi, that's amazing. well done . where r you from sir ?

[@trapps75]

What part of bklyn u located

[@Mike_44]

On my ‘05 Outback XT, when I turn on the A/C, the fans turn on high only, regardless of engine temperature and never come down to low speed.. everything else seems fine. Could this be a bad rad fan switch?

[@user-hh4hc2lt6e]

My 04 tsx came with it deleted and just jumped, what do u think!

[@timdaniels2094]

Thanks!

[@CarsNToys]

Thank you, Tim. I appreciate it! Stay well.

[@asonii-7460]

i have an issue. i replaced mine after confirming it does not work. the ac would kick on both fans and if i jump the connection, the fans turn on. but even with a new fan switch, they still do not kick on. would it be something else? literally everything in my cooling system excluding my water pump has been replaced with mishimoto parts, and they all have less than 1000 miles on them. the fan switch was a mishimoto one too. idk where to go from here update: solution found. it was the thermostat. after a lot of testing i realized the bottom hose was significantly colder than the top hose, and the top hose nearly singed my hand from touching it. i guess even near new performance parts can fail from almost nothing lol

[@keenowl1410]

Is this different than the coolant temperature sensor ects? This is a specific fan switch?

[@sheldondavis716]

I think the coolant temp sensors will be on the block and the fan switch will be on the radiator

[@karlmarxman]

will this work with three wire switches?

[@christine6606]

i tested the relay, fuses. they are all good. itested the cooling/ac fans by using paperclip. The fans are working . So I replaced the cooling sensor. But the fans still dont work. What else is the problem? Thanks.

[@vajaynunthandass676]

Very good video. Where is the thermostat connected to for electricity

[@livetoinspireall2755]

If you are referring to the sensor he was holding; the connector for it is the piece that he stuck to the prongs into in order to complete the electrical loop and allow the electrical current to reach the fans. I tested mine by checking the continuity when the switch was hot and cold. It rules out the switch but not the wiring so I will do this to confirm the $100 relay is bad and not the wiring harness section

[@tedlahm5740]

Serious question. Are the electric fans VARIABLE SPEED? Depending if car is moving or standing in traffic?

[@andyl9920]

Did u test this without the A/C on?

[@TheHelado36]

Is that switch normally open ?

[@HanifEFIMechanical]

Nice

[@kamranbeitarpour3060]

Hi,my radiator fan not working same as before,when i pul of wires from sensor,fan start working fast. also when i use AC fan working not fast.(volvo v70 2012 diesel)

[@johncruz1950]

Hai! Hope you notice me. I just notice my radiator fan(driver side) stop running when the temperature reach at 98c above but my condenser fan is running. But when in a cold start like below 96c both fans running but radiator fan is running at low speed while condenser is running at highspeed. but when it reach to 98c my radiator fan stop running? why is this?

[@Socalrg69]

my question is, do i even need the fans on all the time, they always tend to start automatically when i turn on the car, im constantly comtemplating on how it works

[@user-lo9gk3oi3w]

Hi sir.I have problem while engine cold everything ok when engine hot fan work and non stop until i stop the engine.Radiator,fan,coolant,coolant cap changed with new one

[@Jokessss]

How do i get my fan to spin the other way? I have a mk3 golf and my connector has 3 of those metal things not 2 like yours

[@richieray04]

I replaced my cooling sensor it worked for a few hours... Then the fan wouldn't turn off so I had to disconnect it manually. Now it's not kicking on at all... I checked the relay box and the cooling fan fuse has a bit of melted plastic on one of the prongs. I switch the fuses with one I had with the same voltage but the fan will not kick on... My fan is about a year old and it still works because I tested it with just the battery hooked up to it... Idk what the issue could be...

[@bharatsinghrathore2728]

In my honda accord after ignition when I turn on AC, radiator fan runs for few second and then stop. Not getting clue where it's missing.

[@Bfocus23]

What if it’s a three prong how do you test that

[@fandf1449]

when we do the check in this way the fans turn on but for 2.3 seconds and stop working, what could be the problem Thanks in advance

[@stevembugua7495]

Can someone assist please. I have been trying to replace thermostat in Honda Partner 2008 but cannot remove the housing after loosening three bolts. How many bolts are there in total?

[@Chrispena86]

3

[@turdsgarageandcustoms]

Nice Honda 😜

[@user-bg3nw5re5p]

Temperature switch is broken inside so now I need help how to remove it

[@Benny-dv7xm]

I need help to lean this gas sucker-out. If it can hold perfectly clean for two hours after coming off the highway despite that the operating temperature drops way down at cruise speeds then there has to be a second map or second set of idle values. This is confusing for me because it wasnt an issue of FWD limp mode I was in AWD normal mode but at idle for two hours and it took up to 10 minutes coming off the highway. Shut the car off for a short time but it is at the same temperature and it starts that flooding the car stinking ass crap again. Either way of the car was in open loop because the o2 sensors arent working correctly it was defaulting to internal values at the start only and is looking at throttle position, engine coolant, map sensor values because everything else is disconnected except the o2 sensors but it already has codes against them so it is disregarding them. I saw where there is this open deck\ closed deck situation and where the cylinder will actual regularly move. How do we Identify closed deck blocks especially if there is a bigger version that allows for meat to start from to be able to sleeve an engine? What sleeves won't move in a Subaru engine? 3)On one guys earlier tonight he was talking about using an o-ring to seal the engines when running 30 psi boost. What is a good functional persons reference for that topic?

[@gail6904]

only one of my fans turn on after this test said resistor bad its a 92 hyundai excel but cant find part anywhere'

[@tom4342]

You know where the fan sensor might be on a 92 sentra?

[@stefan4441]

My radiator fans come on when I unplug the connector of the cooling fan switch AND go off when I short them like u did. Why is it the case.

[@curtishargrove8166]

Having the same issue. Did u find out why

[@stefan4441]

not yet @@curtishargrove8166

[@bessarion1771]

how to do it with 3 prongs?

[@user-xb1rh1um5b]

My fan is running as soon as I switch on the car while it's still cold

[@FredY-cg6mi]

Hi, just wanted your take on an issue I'm having with my car. Apparently, my radiator fans don't work with the AC off. Someone mentioned changing the coolant temp sensor. If I leave my AC off and just start my car and pull the connector to the sensor, the fans start running. What could be the problem here? Appreciate your advise. Thanks.

[@owensharp8568]

probably a dead diode between your AC fan switch and thermo switch. but will depend on how its wired up.

[@FredY-cg6mi]

@@owensharp8568 thanks for the reply. Forgot to mention that the vehicle is a 2003 Toyota Camry.

[@soniqdreamscape2008]

Same here. Unplug the switch and the fans start. Touch the leads together with a wire on the switch and the fans stop.

[@Roanadventures]

@@soniqdreamscape2008I’m having the same issue. Did you figure out what the problem was?

[@soniqdreamscape2008]

@@Roanadventures it was a bad relay

[@songsfromthelord888]

Thanks so much for sharing this valuable information...🙂 Remember that God loves you, and wants you to love Him too 🙂

[@BryanG830]

On my car the cooling can doesn't turn on anymore not even if the ac or heater on. I was able to tap the fan motor and it came on but now it don't turn on at all.

[@obdaking]

Probably the motor needs to repair or be replaced

[@MandeepSingh-hn4jd]

I'm facing issue, my car fan not start even if hut 98c.

[@chrismartinez8433]

When I jump the switch it doesn't come on so what what would be the problem

[@julaiarnold641]

switch socket, fan motor, relay or fuse

[@Susan4ten]

Great vid! Do you know where the cooling system temperature sender/sensor is located on a 1999 Oldsmobile Intrigue? The fans work and the fans’ relays are good but I can’t locate the cooling system temperature sender sensor to test it and replace it. Thanks.

[@ChrisEbz]

slooooowww ttaaaaaalkkkkiiiinnnngggg

[@williamtolli1450]

just turn on the ac and the fans kick in to test the blower moters

[@bernardwelff8089]

Thanks William I did that and my fan kicked in. Thanks again for the advice so there must be a problem of some sort with the sensor or whatever its called.

[@davidmurphy6067]

That dont test the switch to see if it's closing or ohm change

[@kenzo4Ever]

Exactly David ! 😅👍 I think it's a good idea to do wiring in series with that switch in order to get a small lamp to be on once the switch is close, it's feasable. What I don't know how to do it is how to do the same as above once the fan starts spinning.

[@lovelymendoza4386]

❤️

[@csnr355]

What if my fans didn't turn on after the bypass was done?

[@OHHyaKnow]

Bad fans relay or fuses

[@jaimeguillen7598]

Ok what if fan does not turn on and I just hear clicking sound?

[@IVAN2233]

Replace the motor

[@owensharp8568]

fan motors are dead. the clicking is the relay which is then working fine.

[@great4ever845]

I hear clicking sound while driving

[@bubbaclaypoole7579]

fan switch on hyuniu

[@jtjimenez05]

Ect sensor showing -40?????

[@willfulltruth9720]

I love randomly coming across new potential he interesting videos love algorithm sometimes only when they benefit me in the knowledge of my mechanical mind to handle my shit on my own and man up like the female LGB fucking question don’t wanna get blocked on this fucking Fred…

[@dustythibodaux]

What if you do this and the fan does not turn on? All fuses and relays are good. Fans are brand new and do work.

[@017hamilton]

Sounds like you have no 12 V power you can check it with a cheap multimeter really easy

[@dustythibodaux]

@@017hamilton I figured it out. Thanks

[@crazyboriskb]

@dusty what was the problem, I have the same issue

[@dustythibodaux]

@@crazyboriskb the temperature sensor in the radiator.

[@nashuakinshu4057]

Hi! I'm having that problem you're describing

[@avuxeni]

This video is short

[@Mr.Freeze8754]

👎👎👎

[@harlzaotearoa7769]

I have a 2005 odyssey. Both fans turn on as soon as i start the engine and they stay on untill i turn it off. Could you tell me why this happens?? Cheers

[@macksanders5126]

My search was for a HYUNDAI XG 350 AND IT PULLS UP A HONDA

[@pandikristo5005]

This video is bullish. When you take out connection the fan turn on .When the fan doesn't turn on the sensor cooling no good. And need to check connection have 12v.

[@salvadorayala8266]

Thanks

[@balsonnaoshekpam6240]

Thanks