Ok I searched and can't find an answer.. here is the problem.

I have and '88 IROC with dual cooling fans. During highway driving my car runs cool and it warms up quite a bit in town/city driving, but its never gotten hot or overheated. I have never seen the 2nd fan turn on.

If the car is warm and I stop (say to park in town) and the fan is running.. the fan will turn off with the key. I can come back an hour later and fire up the car and the temps are still warm and the fan will instantly turn back on.

Is there a wiring problem?? The way I see it, is if the car is warm and the thermostat says to turn the fan on, it should be on whether the key is engauged or not.

Also, why have I never seen the 2nd fan on, even when the temps are very high?

 

Turns off with the key. IIRC, both fans should function when you switch on the AC. Might try it as a test.

JamesC

 

Sounds normal. I believe the 2nd fan doesn't turn on until 243°. When I was having cooling problems, often I would shut the car off and then turn the key to RUN and the 2nd fan would turn on. 1st one would stay off unless I started the car up again.

 

I believe the following is from Willie's Fan Control article:

Primary Coolant Fan Turn-On System
Factory Circuit Operation
On TPI engines, the primary fan is controlled by the ECM and A/C head pressure. The ECM grounds the coolant fan circuit when the coolant temperature sensor indicates the temperature is greater than 222° or when the A/C head pressure is greater than 232 psi and the vehicle speed is less than 35 or 40 mph (depending on application). When this circuit is grounded, the fan relay is energized and voltage is applied to the fan.

Secondary Coolant Fan Turn-On System
Factory Circuit Operation
On some applications, the secondary fan is controlled by the ECM, A/C pressure switch and a temperature sensor, similar to the primary fan. On other applications, the ECM is bypassed and only a temperature sensor is used.

 

thanks guys, I thought for sure there was a problem some where... I think I'm going to look into modifying it somehow so the primary fan will run with the key on OR off..

 

If the motor isn't running and isn't circulating water/coolant, a fan wouldn't seem to be of much use .

JamesC

 

ah, good point.

 

You will also kill the battery very quickly running the cooling fans when the key is off. You have no control over them at that point, and since the thermostatic switch is in the cylinder head, you will run the fan for a looong time before the switch is cool enough to shut off.

If you wanted to run a parallel switch to run the fans while you are watching it (key off), that is a common thing for drag guys, they can cool while waiting to run in the staging lanes.

 

Do you know which fan is the primary on an `88 Iroc and which relay is for the primary fan? My set-up is stock and I have problems similar to yours and can`t find reliable info about the fans.