If I turn on my heater, the rpms surge up and down. When its surging, the AC compressor is cycling on and off every few seconds(needs a re-charge). But why would the AC compressor even need to turn on when I'm using my heater?

Any help is greatl appreciated. Thank you.

 

The defroster cycles the ac on and off its just the way they make them. I dunno maybe someone can explain why. I personally just unplug the ac pressure switch when it gets cold. Dont need anymore cold air.

 

Ahh thanks. About that pressure switch, where is that located? Thanks for the reply.

 

The reason they do that is because it makes the defroster work so much better. Most of the actual work that the A/C system does consists of emoving humidity, not cooling the air; so running the compressor multiplies the effectiveness of the defroster by supplying dry air instead of moist air.

If your A/C cycles when you use it, put some Freon in it. You'll find that your defroster will clear your windshield in a small fraction of the time it takes without it.

The compressor is called for when in defrost mode, but not in heat mode however.