Cooling Fan does not stop


#1

Yesterday, I had to accelerate really really fast…ever since then, my fan does not turn off (when the car starts). I just started the car cold and it is running.

I think the fan relay has gone out. I’m not sure which fan exactly…but when I opened the hood, I see that the fan behind the radiator is the one that is spinning.

Can anyone confirm that the relay for the fan is in the main junction box under the hood (near the front left strut)? Can I put the relay out (by hand) while the car is running? Can I also drive to work for a day or so with the fan on while I wait for a fan relay?


#2

I would much rather have the fan running than have it not running


#3

Ok, there are 2 fans…side by side (one is rad fan, the other is the AC fan). I removed the “Fan No. 1” relay…the radiator fan stops working. However, the AC fan still keeps going (AC is off).

I see another junction box for AC Fan #1 and AC Fan #2. I guess those relays also blew out.

So I can keep running this for a day or 2 while I get the relays correct? Don’t want the fans to burn out. Although I do prefer running it since I’m in a lot of stop and go traffic so it provides better cooling.


#4

If you would include the make, model and year of your vehicle it would make it a lot easier to troubleshoot your problem. I would not advise removing and replacing relays or fuses for that matter with the engine running. I don’t see a big problem with driving your car back and forth to work with the fan running until you find the problem.


#5

Sorry, it’s a Toyota 2000 Corolla (CE 4-spd auto) with 60k miles. When I shook the fan relay, I heard little pieces moving inside it…so it’s probably broken.

Would just leaving the fan on permanently burn it out? I actually prefer it since majority of my work commute is bumper to bumper.


#6

well, if you found relay, you have more mechanical sense/ability than 98% of most folks. you dont have to worry about your 15yr old elec fan motor suddenly wearing out.


#7

Those fans can run continuously until your fix. I would feel those relays after a drive to make sure none are hot. That might mean there’s a bigger problem. We still don’t know why those relays failed. Accelerating “really fast” shouldn’t cause relays to fail.


#8

Well, yesterday afternoon was really hot. In the morning, we had massive congestion (it was bumper to bumper for almost 30 minutes). The fan was turning on and off every couple of minutes (it turns on when the coolant hits 206…it cools down to 190).


#9

Actually, you’re driving environment might have caused the relay to fail, with many on-off cycles. But are you saying it’s working now? You replaced it?

Edit: Oops, misinterpreted the previous comment, which refers to before the fan stuck on.


#10

what temp does it run when the fan turns all the time?


#11

i would swap the relay for a know good one first to rule that out because its free and easy then get into the more complicated stuff if that doesnt work. i actually fried the transistor in my pcm causing my fan to stay on in my race car even though it was my own fault and probably isnt common with oem computers its something i wanted to share.


#12

No, it’s not turning off. Normally, when the coolant temperature hits 206, the fan turns on and runs until the coolant temperature hits 190 F.

Now, it is on all the time without turning off (EX: coolant temperature is 100F). When I shake the relay, I can hear small pieces of it moving inside.

My guess is there is a failsafe, so if the relay fails…the fan just runs all the time.


#13

I wouldn t worry about it, unless the relay gets really hot, its probably shorted out, hopefully in the failsafe manner you indicated.


#14

the contacts could be arcing together. cant you just swap it with for say a fuel pump relay (if there the same on your car) to see if the relay is the problem. because it could be something else ill check the wiring diagram on alldata when i get home to see how your car is wired


#15

If you know what relay is bad, why in the world would you not replace it? Sure you can just let the fan run all the time but why? In my mind I would figure pay for he relay now rather than pay for the fan + relay later. To me it’s a no-brainer.


#16

Something is calling for your fans to come on. For it to be the relays they would have both failed the same way at the same time. It could be a fan control module (if you have one), your computer (if it controls the fans) or the a/c circuitry because the a/c calls for both fans to come on but overheating usually only calls for one.


#17

This is so weird. Now the fans work correctly, it turns off when the coolant temperature gets to 190 F. The sensor is reporting the correct temperature because both the dash gauge AND my language report the correct temperature.

Maybe the very sudden and fast acceleration and engine load (had the AC on) “confused” the computer or caused something to be temporarily stuck causing the fans to run nonstop.


#18

great i love the problems that disappear on there own :confused: because you dont get to fix them and they may pop up again later happens all the time with electronics. if you need me to look up how its wired you can figure out exactly what controls that fan.


#19

I have an early 90’s Corolla and I’ve had the electric radiator fan fail a couple times, in two ways, runs all the time the engine is turned on, or doesn’t run at all. Running all the time is the better failure mode. At least you have cooling until the motor burns out, which it will eventually do if it is running all the time. But at least you have some time to fix it.

I don’t have AC so can’t be of help if AC is involved.

For me at least, the problem was, first time, the wire that powers the fan in the wiring harness got some battery acid on it and a splice got eaten through. The second time the tan’s coolant temp switch was faulty. Neither time was the fan relay to blame.

On a 2000 your Corolla may not have a fan coolant temp switch. The fan might be computer controlled, based on the coolant temp sensor reading. You’d have to consult a factory service manual to find out. If so, besides the fan relay, consider the coolant temp sensor as a possibility too. Those are more robust than the coolant temp switches, but they do sometimes fail.


#20

I’d still replace the relay. I’m pretty sure they shouldn’t rattle.