SNET Telly

Two questions,

1. Does the cpu tell the fans to come on when the A/C is on?

2.Why don't my damn fans come on?

The relay is good. the fans are good. They come on with the A/C. Sometimes they come on when I turn the car back on after driving, but can't reproduce the effect. The only thing I know of left is the cpu. I've tried changing the enable, disable, and speed disable for the fan1 and fan2. I've tried the using the stock bin. Nothing works. My laptop doesn't work so I can't hook it up to the car. I've unpluged the temp sensor on the intake and the engine changes idle quality, so I think the sensor is good. When the fans do come on during that rare ocation after stoping and starting the car back up, the fans will still run if I unplug the temp sensor. Could be the secondary fans switch but I thought it just turned on one fan, not sure though.

Please Help!!!!!!

slinkt

Check the fan pressure switch. And yes, the ECM tells the fan to come on with a/c so that the condenser will operate normally.

If you look at the wiring diagram, there is the fan relay running to the high temp switch (fail-safe) which cuts on at like 250F. It also runs to the ECM. The ECM will turn on the fan through the fan relay when a/c is engaged. The fan pressure switch is what operates the cooling fan at normal temps, it is downstream of the ECM and the fan relay. So, if your fan is coming on with the a/c this means that the ECM is most likely working properly as well as the relay. However, if your fan will only come on at almost boiling temperatures with the a/c off then it must be the fan pressure switch.

I had this problem and overcame it for a while by just running the a/c when the engine temp got over 200 degrees. But I when I looked at the diagram it turned out to be a simple fix...

SNET Telly

Thanks for the info. Is the fan pressure switch the one on the pass. side head? If so where is the fail safe switch located at?