My 88 gta runs hot in traffic. It concerns me when the temp goes above 220. I looked with the car running and the fans were not on. the temp was 225. where do I start. I am going to unhook them and put power to them to see if they work. other than that I know about a relay and thats all. Thanks

 

Put your car in diagnostic mode and see if the fans go on, to do that just connect the terminals A and B(upper right two) on the ALDL below and to the right of your steering column. This should turn the fans on. If not, check the relay beside your radiator on the passenger side front of the car.

 

Try replacing the cooling temp sensor. I had the same issue and that fixed me up.



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Kiss_My_SS
1992 Camaro RS/Heritage Package
1996 Impala SS
1985 Good ol' Chevy 4x4 Truck

 

it might be the fusible link or the fan switch sensor..

 

After testing the ECM try this: With the key in the "on" position pull the temp sensor out of the head (drivers side) and ground it. This should kick the fan on, if not I would replace the temp sensor. If you have a manual, I think it goes through the steps to diagnose the problem.

I left the temp sensor grounded so the fan runs full time. I know most people would disagree with doing that, but it keeps my car running cool in this Texas heat. I might have lost some MPG, but the original engine has 265,000 miles and is still humming. For me, the cooler the better.

 

I turned on the A/C and the fans work. so now I know they work. But only when the air is on. I will replace the relay next to the radiator. then the coolant temp sensor next if the relay dosen't do it.

 

O.K. I went to the ALDL and jumped A and B. the drivers side fan came on. the passengers didn't. I unplugged the relay and the one fan turned off. so now I know the relay is good and one fan motor is good. I will check one more time to see if they both work when the A/C. is on. The only thing left is the sensor.

 

One more time. Are there seperate relays for each fan? if so where is the other one? I took the connector out of the working fan and ran the wire to the other fan and it came on. So I eaithe have a bad relay that I haven't found yet or a wiring problem. Once I get both fans to work they wil still only come on in diagnostic mode or when the A/C is on. Does it sound like a Collant Temp Sens.

 

On a dual fan setup one fan is for the AC and the other fan is run through the system.

You know both your fans work when you did the testing and they came on.

You know the relay works.
The only thing left is the temp sensor and the fan switch.

My guess is it's the temp sensor has gone kaput.
The temp sensor tells the computer the engine is hot enough to turn on the fan.

And I think the fanswitch finalizes the deal and kicks on the fan.

 

the driver side came on when I used the ALDL block. the same fan came on when I turned the A/C on. you are telling me that the other fan should have come on with the A/C. If this is true then does the diagnostic mode cut the A/C fan on?

 

The sensor on the Driver's side head controls the Temp Guage only. I have never tried the one on the Passenger side head, but I would say that if you ground that one, it should turn on the Fan (on a single fan car) or Fan #2 (on a dual fan car).

As for the ECM, it does not turn on the Fan (or Fan #1 on a dual fan car) unti the engine sees 228*F based on the CTS (in the base manifold on the front of the engine on TPI). You need a scan tool to check this as the Temp Guage is FAR from accurate AND it has nothing to do with the ECM.

As for turning on the A/C, this is occurs because the ECM only looks for an "A/C Request" and your Vehicle Speed, it has nothing to do with Coolant Temp. When the A/C is on, your Fan #1 should remain on until around 37 mph.

IF the 225*F was correct, then you have not met the minimum temperature to turn on the fan. If the 225*F was in fact 228*F, then the fan SHOULD come on. Again, you need to get a scan tool to see what the CTS reading is.

 

You should search the archives and read about this common problem. One important thing I have learned from this though, is that the fans are not supposed to come on until a very high temp under the stock setup. The general consensus is that this is too hot. Mine did exactly this until I installed a hayden adjustable fan relay (easy).