fans wont turn on by themselves

[maroman88]

cars been gettin really hot and the fans havent been turning on, i grounded out the wire to the coolant temp sensor and they came on and now they wont go off until the car is turned off. sound like a bad coolant sensor or what??

[JSPERFORMANCE]

or fan relay

[enRo]

fan relay, up by the driver side firewall. they sell them at autozone for pretty cheap.

[BonzoHansen]

I'm guessing if he grounded the fan switch and the fan came on, that is the issue. If it were the relay, I might guess it still would not have come on.

[maroman88]

k i was doin some research, there is a fan switch on the front driverside head? that can only be seen from underneath? i grounded out the one thats right under the TB on a TPI i think its a coolant temp sensor

[BonzoHansen]

You should not just ground things for fun. That is how you break things, like ECMs. Does your car have a fan switch, or is it controlled by the ECM? Find a wiring diagram and go from there.

Which car is this?

[maroman88]

91 Z28 5.7L TPI

its controlled by the ECM on TPI cars, i think i was readin about the fan switch for TBI cars my mistake

[BonzoHansen]

Man, the AutoZone site is FTL for me right. Way too slow. But here is your wiring diagram. (http://autozone.com/images/cds/gif/large/0900823d80163fec.gif)

CTS location: Under hood, center, upper engine area, rear of water outlet, mounted in intake manifold

No fan switch in sight.

Based on what you did, there are only so many things it could be. Grounding the CTS (don't do that again) made the fan come on, so to me that eliminates wiring harness issues and the relay. That leaves the CTS or the ECM. Is it throwing a CE light?

All according to this diagram: You have 2 fans, a main one turned on by the ECM, the other turned on via the AC being on or an auxiliary fan switch (where is this located?????). Each fan has its own relay. Does the one fan come on with the AC?

Change the CTS – they are $12. ECM is $100 (all at rockauto.com)

[alamantia]

if i remember correctly that fan switch is in the head, i thought it was on the passenger side though, not sure about that now sitting on my computer at work. I know that sensor for the gauge / idiot light is usualy on the drivers side head between the #1 and 3 cylinders. I remember switching the thermostat in my 91 RS 305 TBI from teh stock 195 to a 180 and buying the fan switch from summit to click the fans on at a lower temp to match the new thermostat. When I did it i noticed that the knock sensor was right below it. Do your fans turn on when you switch the A/C on???

[maroman88]

if i remember correctly that fan switch is in the head, i thought it was on the passenger side though, not sure about that now sitting on my computer at work. I know that sensor for the gauge / idiot light is usualy on the drivers side head between the #1 and 3 cylinders. I remember switching the thermostat in my 91 RS 305 TBI from teh stock 195 to a 180 and buying the fan switch from summit to click the fans on at a lower temp to match the new thermostat. When I did it i noticed that the knock sensor was right below it. Do your fans turn on when you switch the A/C on???

yea on a TBI it is there, on a TPI its on the front of the lower plenum

thanks bonzo, i was workin off of chevythunder.com and got the same info

im guna go try the AC in a little while and get a new coolant temp sensor tomarrow ive changed it in the other camaro b4 and is no big deal

[maroman88]

yup they turn on wit the AC

[maroman88]

k i found my scanner and had a code for the coolant sensor, i changed it and eset the computer and it hasnt come back.

however the temp reading from the computer is about 40* less then what the guage says. i got a temp gun from work and shot the waterneck on the manifold and its reading almost exactly what the computer reads. why are cars a pain in the ass lol

wat the hell

[BonzoHansen]

Better the gauge high then the low, I suppose.

Otherwise, all fixed??

[maroman88]

yea i guess so, the fans did come on when the computer said the temp was at 228* but the freakin guage was pinned lol

[BonzoHansen]

Might be time for a new gauge sender too.

[maroman88]

wheres that located?

[BonzoHansen]

Probably in the side of the head.