Fans don't come on when engine is hot

I have a '94 GS-R and all of a sudden the temperature gauge started almost maxing out. I did some "testing" and saw that the two fans in the engine compartment DO NOT come on when the temp gauge is showing hot. The fans DO come on when I turn on the A/C, so the fans aren't bad, and the fuses aren't bad, and (from looking at the wiring diagrams) apparently the relays aren't bad. The check engine light DOES NOT come on, so it seems like the computer doesn't notice any problems. The gauge seems to be working correctly (it slowly gets hot, then cools down when I turn on the heater, just like I expect it would), so I think that means the engine coolant temperature sensor is working correctly. Basically, everything seems to be working as it should, except that the fans don't come on when the engine gets hot. All I know about the operation of the car is what I read from the Chilton guide I bought, so maybe it's more complicated than I know. I would really appreciate any help you can offer me. Thanks.

Nick

Fan switch, maybe?

you can jerry rig it with a switch if you cant get a new switch anytime soon. Assuming it is your fan switch and not the fans themselves.

I did it on my Integra for a little while.

it could just be your thermostat.

either your not waiting long enough for the car to heat up or, try this. i can't remember the name of this but, it is the sensor on the thermostat housing. take off the wire connector and jump it with a small wire. with the engine off. then once it is jumped start the engine. if the fans don't come on then that is your prob.

Thanks for the different suggestions. I'm not sure which fan switch is being referred to...I got the impression that the relays were the only switches, and I'm pretty sure they're good since the fans come on when I turn on the A/C.

The temperature sensor seems to be working correctly, but I guess I should test it to make sure. Even if it wasn't, though, I thought that should set off the check engine light...

The temp gauge maxed out for a bit one time and the fans didn't come on, so at least it was claiming the engine was hot enough. Shorting out the temp sensor might be an easy way to check if the wiring diagram is lying to me about how it's set up...thanks for the suggestions.

I'll try some things this weekend and let you guys know what I find. Thanks again for your help.

BTW, I think I might wind up going with the hard switch wired to the passenger compartment if I can't find a quick fix :)

the sensor i'm talking about on the thermostat housing is a different sensor than the one for your gauge. there are two seperate sensors. i had the sensor go out on the thermostat housing 2 months ago. and jumping it is how i figured it out.

Try turning the AC on. The fan should turn on then.

I have a '94 GS-R and all of a sudden the temperature gauge started almost maxing out. I did some "testing" and saw that the two fans in the engine compartment DO NOT come on when the temp gauge is showing hot. The fans DO come on when I turn on the A/C, so the fans aren't bad, and the fuses aren't bad, and (from looking at the wiring diagrams) apparently the relays aren't bad.

Nick
um he already tried that there buddy. try reading alittle.:shakehead

does sound like a thermostat problem

Thanks for all the suggestions, guys. It turns out it was just a simple thermostat problem making the temp gauge go up. My car runs nice and cool now. This is good, but I never did figure out why the fans wouldn't come on when the engine was heating up...maybe the engine has to get even hotter than I thought. Oh well, it's not an issue now since the car stays cool with a working thermostat (imagine that)

Thanks again

i live in florida so its not cool here at all, and when i go to start my car in the morning i have to wait what feels like forever for the fans to come on. sometimes makes me feel like they are finally going. but integras have an excellent cooling system. always can be better though.

From what I've read:

"We have found that the fan does not come on until the temperature gauge is close to 3/4th hot."--http://www.2carpros.com/makes/acura.htm


"The quickest check of cooling fan operation is with the engine running turn the A/C system on. The cooling fan on the A/C condenser should turn on shortly after the A/C system is activated. A word of caution: the engine in your Acura does not like being overheated. It is too easy to cause damage to the head gasket and checking account if the engine is overheated too much or too often."--http://www.alldata.com/techtips/2003/20030616c.html

Good to see your high temps problem was solved by a simple thermostat.