I'm pretty sure my a/c pump is bad ( when i turn on the a/c the pump is really loud, but blows cold air) anyways, when I try to run the heater it does the same thing...why would the a/c pump enguage when the heat is turned on? OR could it not be the pump and maybe something else that is wrong? A/c being broken is not so much a problem...foggy windows in the morning is a much bigger issue.
As always, any help is appreciated

 

If you are on defrost the compressor runs to help dehumidify the air even if the temp is on high. If you are set on heat only then the compressor shouldn't run. Listen to it outside the car with the compressor off and then have someone turn it on. You should be able to tell if the noise is from the compressor or something else.

 

i'll check that out. I'm sure its the compressor making the noise. I cant remeber if I just tried the heat on defrost or not. Thats good to know though.
Thanks!