2nd Gen Non-Engine/Transmission Heater Controls

[Nate]

When I have the heater on... whether it's in vent, defrost, or A/C, the A/C pump cycles on and off.



I know it would normally do it in defrost and of course A/C, but vent?



Any ideas on what might be causing this? I'm not loosing sleep over it, but I was thinking it might be an easy fix.

 

[Nate]

Coming back to this thread, anyone have any ideas?

 

[DNewell]

I had this issue with my old 87 Chevrolet. I think that the switch is bad. You may want to find out how much it would be to replace the switch. This would require pulling the dash off, but this would be the only thing that I can think of...

 

[B.G. Smith]

Problem could be the compressor clutch relay, it is located in the PDC under the hood. Remove it and check for continuity between terminal terminals 87A and 30, should have continuity, check also between 87 and 30, should be no continuity. Resistance between 85 and 86 should be 75ohm plus or minus 5 ohm. If all check ok then it is either in the switch as suggested or the PCM. bg