A/c

My a/c compressor is clicking on and off every 20-30 sec how should I troubleshoot this please.Thanks.Also my Hvac is not working properly and has defaulted to defrost and floor ,checked vaccuum leaks and actuator and programmer cant figure out,but not worried about this unless it affects compressor.When defrost is on and idling I hear click ,click pause click ,click.

When the defroster is on the AC will kick the compressor on. I would fined a guage and check the pressure in the system. Usually when the AC compressor clicks on and off like that it means there is low pressure in the system. As for the vents it is doubtful that the ac system has anything to do with the vents themselves.

I disconnect the battery for a bit and there has been no clicking for over a day now ,I bought this car 2 months ago and the lady had the a/c serviced this summer ,it has new rad a/c hoses ,accumulator and they got it running good ,so its not impossible but I didnt think there would be a leak,and freon should have been topped up.

There is a vacuum tee on the top of the upper plenum that feeds vacuum to the HVAC system. Since yours has defaulted to floor/defrost blend, I would bet you have no vacuum getting to the control head/vacuum solenoid inside the car. I agree with GTP on the compressor issue, it sounds like low refrigerant pressure, but it could also be just a bad pressure switch. You didn't specify what year the car is, but if it's pre-94 and came factory with R-12, and they converted it to R-134, you must replace the low pressure switch for proper system operation.

Hi sorry richtazz I thought it was in my sig ,changed it now I have 1990 sse.Where is pressure switch?Also I have been through the Hvac programmer adn getting good vaccuum through main supply (purple and black hose) and vac pressure is 28-20 hg.Is it possible that it is common to lose refridgerant when a new system is put in.Also I disconnected battery to reset and it seems to be okay right now ,think that could be?
Thanks for responding .you guys a great and Happy New Year.

The switch you're looking for is near the accumulator, or the aluminum can under the hood. If disconnecting the battery got it working, great, maybe the programmer re-set itself, let us know if it acts up again.

The switch you're looking for is near the accumulator, it's the aluminum can under the hood. If disconnecting the battery got it working, great, maybe the programmer re-set itself, let us know if it acts up again.

Richtazz my compressor seems to be ok ,now played around with hvac programmer I seem to have a/c coming nicely out of middle vents but heater still defrost and floor any ideas.thanks for replys

Check for a vacuum leek under the hood to the left and down a little of the brake booster , mine would stay on defrost all the time even with the air on.