Radiator fans not coming on


Asked by wcaxzero Mar 09, 2016 at 11:28 AM about the 1994 Toyota Camry LE

Question type: General

1994 Toyota camry 4 cylinder 5sfe engine.
My fans aren't coming on when I turn on my car or
when the car reaches over 200 degrees F. The
engine just overheats.
I checked the Engine Coolant Temp. Sensor and
tested the Thermoswitch (cooling fan switch
mounted near bottom of radiator) and they are
both good. Relays and fuses are good as well. I
tested them and checked them with a power probe
and a multimeter.
When I unplug the connector that goes to the
Thermoswitch (bottom of radiator) both fans turn
on and cool down my car preventing it from
overheating but they stay running unless I plug it
back in. What could be the problem?
Also, the fans turn on with the AC button pressed
in and turned on. The fan or fans don't turn on by
Any help is greatly appreciated.

16 Answers


So I can only think of one thing. When you said that they kick on when you unplug the wiring assembly I thought "ok its that harness or connector" but after you said that the fans will kick on when the A/C is activated, it made me second guess my first assumption. I looked at a wiring diagram for the Camry and I believe that my first assumption is correct. Unless for some reason you have a faulty replacement stat (which can happen), its my best guess that its that plug, you should be able to cut one from a wrecked Camry or Lexus ES300 (92-95) as they are interchangeable cars, and wire it yourself. Electrical on cars is one of the most expensive tasks to DIY. If you do not properly ground or wire the new components, it can reek havoc on every electrical system in the car. I would say if you're relatively confident you can perform this task, I would swap that plug/wiring harness. Best of luck. Let me know how it turns out, Ill monitor your post, I am interested to know if that fixes the issue.

4 people found this helpful.

Hey thank you for your response. It's been raining a lot where I live so haven't been able to do anything, but one thing. I pulled another thermoswitch (radiator coolant fan switch) from the junkyard and installed that in. The one I took out was corroded but cleaned it up and decided to test that one. (With KEY to the on position - DO NOT START)I unplugged the connector that connects to the switch on bottom of radiator (Fans came on) and connected it to the switch I cleaned up (Fans turned off). I held the wiring in hand, while I heated the switch up with a mini hand held pen-size torch to see if the fans would come on. After about 2 minutes of applying heat or so, both fans came on (they stayed on for about 2 minutes as I cooled the switch down. My radiator looks pretty old but don't want to dismiss it so quickly (I just bought the car a month ago and don't want to start throwing parts at it until I pinpoint the issue(s)). Other than that, I will most likely flush the coolant and remove the water pump to check it for corrosion inside. I will also be taking the thermostat out and testing that as well. I'll keep this page updated as I can imagine I am not the only one who has ran into or will run into the same problem. Another question that is probably confusing some is "aren't my fans supposed to run when I turn on my car?" I would assume for this car No. I could be wrong but I am certain that the fans should come on at a certain vehicle operating temperature (mines somewhere around 185-210 degrees Fahrenheit). For anyone reading this, check your manuals, look online, or buy a manual.

1 people found this helpful.

Before I confuse anyone: The Switch I took out was from my radiator which was corroded * ...and this wasn't like a rinse off thing. I applied pressure and scraped off some with my fingernails and kept drying with a shop towel. This is the same Switch I tested (heated with torch that turned the fans on) - I haven't tested the other switch which I pulled out from the junkyard and installed on bottom of my radiator.

1 people found this helpful.

Sixfootsix_car_guy I found this website where someone asked a Toyota Master Mechanic about the same issue I am having. Doesn't really solve the problem but he does mention that if the plug is disconnected from the switch and the fans come on, it indicates all relays and wiring related to this issue are working. Just thought it would help to post this. Again, I appreciate your help. I'll keep this page updated. Here's that website http://www.justanswer.com/toyota/6ptgr-1992- toyota-camry-cylinder-cooling-fans-not-working- replaced.html

4 people found this helpful.

Hello, im having the same issue. just wondring if you were able to fix it??

3 people found this helpful.

Already replaced Fan switch, and Coolant temperature sensor, and still nothing. Fans will only turn on once i disconnect the Fan switch plug. Thank you.

3 people found this helpful.

Hi there Bnb, yes I was able to fix the issue. I replaced my radiator because it was corroded and it was fully rusted. My fan switch was corroded as well so I cleaned it up and tested it. I also bought a new water pump and installed that because my old one was pretty corroded as well. I cleaned out my two radiator hoses (upper and lower) since they had corrosion as well. I also bought a new thermostat because I wanted to replace it as well (since its pretty cheap)...and come to find out that there was no thermostat in my car. Anyways, you say that you replaced the Fan switch and Coolant temperature sensor. Did you replace them with new ones? Or with some from your local junkyard? You also say that your fans only turn on once you disconnect the fan switch plug. They turn on when you have the key on ACC-on right? (not start or cranking) then disconnect the plug, am I correct? Assuming that you have the key in the ignition and turned to ON (before cranking-but do not crank) and you unplug your fan switch connnector...the fans should turn on. If so, this makes sure that your relays and all eletrical wiring is good. Does your car overheat? The fans don't come on immediately once you start your car. You have to wait a little while til your car warms up and gets to operating temp. Once the car gets to operating temp, you fan switch should kick on and send a signal that then sends a signal to your fans to come on and cool your engine down. Let me know how it goes.

5 people found this helpful.

Thank you very much for taking the time to reply man, i appreciate that. (2001 camry) The car was involved in a accident that got repaired so it has a New Radiator and New fans. After refilling the coolant i noticed the fans never came on , and after about maybe 20 minutes the gauge was pointing about 9/10 Hot but the radiator coolant wasnt boiling or steeming. So first i checked the Fan relays which was a Black one and a Brownish 1 and they seemed ok. After reading up on it I replaced the Fan switch , and i also replaced the Coolant temp sensor becuase it broke when i unplugged it. Bummer. Bought both New parts from local store. After i replaced both sensors it didnt do much of a difference, Car gauge still was almost At H in the gauges , so After making sure every electrical plugs were plugged in good and all grounds were grounded i noticed when i unplugged the radiator Fan switch sensor The fans would turn on &drop the engine temperature back to normal level but once plugged back in the fans would shut off immediately . I was thinking it had a short and a bad thermostat forsure or waterpump. Kept on reading info online and i decided to replace the Biggest Fan relay (which was Green in color). After i switched this relay out the car would still mark That it was overheating, the Gauge would be around 8/10 but the Fans finally kicked in and would drop temp to around 6/10 in the gauge. Still wasn't happy with results so After another long night of reading up I decided to Replace the small Temperature Switch Sensor that is right next to the Coolant temp sensor . And Finnalyyy problemmmm solvedddddddddd man . It no longer overheats and the fans are working proper

12 people found this helpful.

Awesome! Hey man, that's great news! I'm glad you got your car back up and running.


Hey guys, I'm having an issue with my '98 Camry overheating. For the past few weeks I've been having to put water in more frequently and I thought it may have been the radiator cap, ( I've had to switch out and it worked) or the reservoir. When my car got hot yesterday, I noticed a leak from the thermostat. So we fixed that but it still got hot. We noticed the fans aren't coming on. What do you think could be causing this?

3 people found this helpful.

Hey Brib...I'm working on an '01 Camry, and it sounds like the same issue you had. I am guessing you have the V6? Mine is the four. New water pump, thermostat, radiator, fan switch (lower radiator). When I unplug the fan switch, the fans come on, but when plugged in, the fans don't come on at all, and the gauge runs 8/10...not in the red, but way too close, and at that temp, the fans don't come on. Any thoughts anyone?

2 people found this helpful.

Update: So, I probably shouldn't have bothered you guys...but I did figure it out, and I need to let you know what I did. There were two sensors I didn't replace, as the manual said nothing about them. on the outlet at the top of the motor there are two: one was Duralast (brand, Autozone) TU179 Temp Switch, and the other is, Duralast SU4007 Temp Sensor...one of those did the trick. I also had done the Duralast SW1434 Fan Switch. So, long story short...this has taken a few years of fighting, and I watch one Utube video and I see some gal replace this thing, and the light goes on...and the car's temp is rock solid, just below the 50%...even uphill. Best wishes. Thrasherguy out.

3 people found this helpful.

Have the same problem tried to earth it out to see if it would turn the fan on but didn't could it be anything to do with the relay, th fan turns on when i move the switch in the fuse box to the right and hole it there but turns off if I let it go... someone help me

1 people found this helpful.

I have the same problem with my Hyundai Sonata 2004 which is 4 cylinder engine. I bought this car a month ago and lately it started overheating in stop and go traffic. I watched a lot of videos and articles replaced coolant temp sensor. Well this coolant temp sensor has 3 pin outs 5 volt 12 volts and ground. Anyway it did worked for sometime like first run then started overheating again fans not kicking on. I tested the coolant sensor it’s resistance going down when hot and high when cold. It’s thermostat is that lower hose. I was checking for thermostat opening by running engine idle and looking at coolant, no bubbles found but coolant flows out of radiator for sometimes and drops down when it gets hot but I don’t see any swirling or motion. Now the car won’t overheating unless you run it for awhile may be because it’s cold outside. Fan do kick on when I unplug coolant temp sensor. I have no freaking idea if this has a fan switch and temp switch. Since fans turning on when I unplug I am assuming all the electrical good. I ran the obd it triggered P0118 code for temp sensor. Need help.

i need help with my 97 toyota camery my fans only go on when i turn off ignition switch but when i turn on ignition switch fans go on can any one help me


Check it. 1987 toyota camry owner. I have had damn near all the problems mentioned above. Everything time something went out within my fans circuitry (relays mainly). I have to mention it would always be after a long drive, ya know when she got a little on the warm side. It always led back to the fan switch. Turns out if you disconnect the 1st fan and run it to a switch on your dash. Over heating will surely be a thing your past. Just remember to always turn it on whenever you get in your car/truck as well as everytime you exit. Wouldnt want any dead batteries. Hope this helped :)

1 people found this helpful.

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