Cooling Fans not coming on A/C??
bigstan50
07-16-2008, 08:24 PM
2000 Pontiac Grand Prix SE
3100 157000 miles.
First little things like control for blower motor will only work on high, Then trac light stays on off and cannot get t/c to come on. This doesn't bother me but may be part of my problem. This has been going on for a while not recent like my other problem.
My biggest problem I had to ground A/C relay to make compressor come on. Now the cool fans won't come on causing it to build to much head pressure and makes the freon release out of high pressure valve.
Only low fans kick on with water temp but nothing with A/C.
I have recharged and checked pressure. Pressure was fine until the fans needed to kick on and they were a no show.
I have checked all fuses and relays showing no shorts. There is power to the relay when ground. My question is could this be my PCM?????
3100 157000 miles.
First little things like control for blower motor will only work on high, Then trac light stays on off and cannot get t/c to come on. This doesn't bother me but may be part of my problem. This has been going on for a while not recent like my other problem.
My biggest problem I had to ground A/C relay to make compressor come on. Now the cool fans won't come on causing it to build to much head pressure and makes the freon release out of high pressure valve.
Only low fans kick on with water temp but nothing with A/C.
I have recharged and checked pressure. Pressure was fine until the fans needed to kick on and they were a no show.
I have checked all fuses and relays showing no shorts. There is power to the relay when ground. My question is could this be my PCM?????
richtazz
07-17-2008, 05:54 AM
The blower motor issue is most likely a bad blower motor resistor. Very common issue on these cars
The ABS/Trac off issue is most likely a bad ABS wheel speed sensor that is part of the front wheel hub assembly.
The A/C issue sounds like the system is blocked. Did you check both high side and low side readings and then compare to a chart that compensates for ambient temperature, or did you just check low side readings?
The ABS/Trac off issue is most likely a bad ABS wheel speed sensor that is part of the front wheel hub assembly.
The A/C issue sounds like the system is blocked. Did you check both high side and low side readings and then compare to a chart that compensates for ambient temperature, or did you just check low side readings?
bigstan50
07-17-2008, 08:26 PM
Check both and gauges read fine but I had to ground the AC relay first in order to get it to do anything. AC worked fine until head pressure builds up pressure and fans did not kick on to cool condenser. Fans will kick on if you hook it up to the battery. So they DO work just not when wired normally and waiting on info to kick on. Its like something is not telling them to kick on. I checked all the relays and they were fine. The other stuff like the blower motor I can live with but I have to get the AC going.
BNaylor
07-18-2008, 10:01 PM
Check the refrigerant pressure switch output. The PCM module uses the pressure switch to turn on the cooling fans as long as high pressure is at least 190 psi and above. If that is good then the PCM module is suspect since it controls and energizes the A/C compressor clutch relay.
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