Compressor cycles with defrost?
 

With cold weather here in New England, I have been using my defrost and heat. I never noticed this on other cars/trucks but when I have my defrost on, and I think even the heat, the ac compressor cycles on/off. What is up with this?

Re: Compressor cycles with defrost?
 

Vehicles from the early 80's and newer are designed to cycle the A.C. compressor every now and then to keep them from siezing up from non-use. All it's doing is circulating the oil in the compressor to keep everything lubed inside. No worries no biggie.

Re: Compressor cycles with defrost?
 

An air conditioning system is mainly used to cool the air that’s going through your vents and defroster. A useful side effect of air conditioning is that it reduces humidity levels. Less humid air being pumped through your defroster equals faster defogging on your windscreen.

Re: Compressor cycles with defrost?
 

It does that on defrost because the a/c drys out the air.. like fog on the windshield for example..

Re: Compressor cycles with defrost?
 

ya beat me to it lol

Re: Compressor cycles with defrost?
 

i was gonna say i havent had a truck that hasnt done it in years

Re: Compressor cycles with defrost?
 

Mine cycles on even when I have the "vent" on. :crazy:

Re: Compressor cycles with defrost?
 

According to the repair manual for my '75 GMC the compressor will always be on in defrost mode. It will cycle off when the evaporator temp sensor (or outside air) reaches 35 degrees.

My original A/C controls were marked in one section as Economy Mode, since the compressor or will not cycle on in those positions (I think it was the positions for Floor only or Vent only).

Bruce

Re: Compressor cycles with defrost?
 

Sounds like something's wrong....:(