Cooling fans keep running.. WTF!

[newbie212]

My beloved 237k miles 1999 corolla (aka the beast) is a little sick.. Her cooling fans keep running no matter if the car is warmed up or just started.. I unplugged both fans for a quick remedy.. Is there a relay that I can check? Where is this relay? Anyone else have this problem? Thanks in advance..

[REN69]

It's probably the temperature sensor, if you find the cooling pipe near the motor where one of the cooling hoses goes in, there should be an electrical plug going into a sensor right on the pipe, that's your cooling sensor and it's either failing or unpluged.

[toyomoho]

These systems are usually designed to failsafe. If a wire breaks, relay fails the fans will run all the time. As such it is not a matter of finding what is causing them to run, but what is causing then not to shut off.

[ghost_ryder35]

coolant temp sensor like ren69 said. costs like $25 from rockauto.com or around $40-55 at the dealer

[newbie212]

I cant seem to find the coolant temp sensor in the car... Anyone know exactly where it's located or a picture of it? Thanks

[ghost_ryder35]

Originally Posted by newbie212

I cant seem to find the coolant temp sensor in the car... Anyone know exactly where it's located or a picture of it? Thanks

located right next to the thermostat housing near the upper radiator hose. if your looking at the upper radiator hose look down to your right and you will see a plug going into a bolt looking thing. that is the sensor

[retiredat44]

There are 2 sensors,, one for the temp sensor, another provides feedback to the computer stuff, and smog.

on Autozone.com it has info and diagrams,, look int he repiar links put your model and year... and it wil show you..

[newbie212]

Hey everyone.. Thanks for the replies... This site is very helpful... Happy Holidays!!

[Kanding]

I just went through this on my 93. Before you buy a new temp. switch, check to see that the one you have works. It should be continuous at cold temps, open circuit at high temp. Next you can check the relays. There are two or three in my car that help to operate the fan. You'll need a car book (Haynes, etc.) to find how to test the relays. Finally, as someone noted, the fan defaults to on; i.e. an open circuit operates the fan, closed circuit cuts it off. Thus, if you have a broken wire anywhere in the path from the temp switch to the computer and back, the fan will operate. I ripped through a bunch of wires in my engine bay to track down the problem, and in my case it turned out to be a rusted-through wire on the opposite side of the engine that fed into some switch on the AC system. Took a long time to track that down and then retape all the wires. Good luck.