Defrost with NO air conditioning

[DFrank]

I think people are mixing terms here. The AC compressor comes on with the defrost, but the AC doesn't. It's functioning more like a heat pump, which may be a more accurate description of the "climate control mechanism" on our trucks. Running the compressor when using defrost dries the air and clears your windshield faster. Because it also functions as a heat pump you get warmer air faster directed up to your windshield. I'm getting luke warm air from my defroster long before my temp guage budges.

So on which settings does the pump kick in, and how is that different from actually running the AC? Is it actually puting colder air up to my windshield even whithout the "snowflake" button being depressed?



If it is running as a heat pump, is the air just running over the opposite side of the coils or heat exchanger?

 

[Crunch]

So on which settings does the pump kick in, and how is that different from actually running the AC? Is it actually puting colder air up to my windshield even whithout the "snowflake" button being depressed?



If it is running as a heat pump, is the air just running over the opposite side of the coils or heat exchanger?

Not sure exactly how it works, but I've heard all AC's now function as heat pumps. If I had to guess I'd say that the AC button controls the direction of heat transfer, and the thermostat controls the level of heat being transfered. I've turned the thermostat all the way to the left while running the defroster, and though the air was cold, it wasn't cold like when it comes out of the air conditioner in the summer. More like ambient cold air.

 

[SLinse]

I just discovered a problem with my HVAC tonight. I believe I have a leak in the AC system. My truck runs on defrost 95% of the time. I am one of those "popcicls" in Fairbanks that experiences the -40. Anyways, When it defrost the AC pump is on, to what extent I'm not sure. My problem is I hear something like an air leak after I shut the truck off for about 10 sec. So I turned on the AC turned the temp nob to cold, and it isn't very cold at all. I guess it will have to go in to get checked out.



If you have the temp turned to hot, and kick on the AC (pushing the button) it will help take the moisture out and defog the windows.