Thread: Cooling fans and A/C issue *need help

1998 Pontiac Grand Prix SE 3100

Problem..A/C and cooling fans won't kick on.

Corrective measures...

Checked fuses..all good
Changed all 3 cooling fan relays..no help.
Direct connect to battery to check fans..they worked.
Recharged the A/C..needed like 10 more PSI..no help.
Changed coolant temp sensor..no help.
Changed ambient air sensor..no help.
Changed Air charge sensor..no help.(runs better after this though)

Previous repairs..
Water pump and belt replaced.
Heater motor blower replaced.
Blower motor resistor replaced. (vents now blow heated air and air from outside)

Fans won't kick on nor will A/C at this point. I have been reading for hours. I read somewhere there is an inside air temp sensor, but I can't find it. I noticed a female connector by the battery with the same color wires as the ambient air temp sensor not plugged into anything. Looked for about an hour for the male connector but I can't find it.

Any ideas or can someone send me a pic of where the connector next to the battery with a yellow and green wires go to?

i got the same connector and nothing to plug it into, no clue as to what its for,
anyways did you check the wire that goes from the pcm to the fan relay?

The connector is likely for a radiator level sensor. If your radiator was swapped, it might not have the hole for the sensor. Which explains it. I hope I'm right

On the fans.. if you drive the car and sit in traffic, what temp does it get up to? Fan's are programmed higher than most of us would think 216F/228F

Originally Posted by pabstman

Hi guys. I just bought a 89 GP 3.1 same issue both fans won't come on. Any answers?

Well I hooked my buddies snap on scanner to the my car and turned the fans on thru it proving the fans the relays and fuses worked. I also check the temp sensor and it was telling the computer to turn the fans on. So the GM trouble shoot manual said it was the ECM. Replaced the ECM and it worked fine. Must have been a bad solid state relay in the ECM board.

Having the correct diagnoistic equipment can sure cut down on the repair time. Other wise it would have took a while to figure it out.

AC issue was a bad clutch on the compressor. I cut a plug off a car in the junk yard and wire up and jumped the AC direct to the battery and it would not engage. replaced the compressor and fixed the issue.