2009 Chevroet HHR LS 180,000 miles manual 2.2 liter. I bought this car new and the AC produces cold air even when it is 110 degrees outside. I have never had the AC serviced. I did use belt lube. I understand the basic idea behind the compressor producing a pressure difference. The AC cmpressor for cooling makes use of the low pressure side for cooling. The defroster is apparently a different concept.The defroster works well in the cold frost of winter and quickly defrosts the windshield. During this time, hot air is blowing on the windshield. Whenever the defroster is on, the compressor is also on. What does the compressor do for the hot defroster?
The AC compressor creates extremely dry air which makes cold humid air not fog up that's why if you ever had a car that only had a heater and not an air conditioner and cold damp weather the windows were often fog up
What happens in the very early hours of the morning when the air temperature is at its lowest? The dew drops, right. The temperate of the air has dropped to the point where it no longer has the energy to carry moisture, and water precipitates out.
The A/C evaporator does the same thing. It cools the air which dehumidifies it. This does two things (A) obviously the dry air won't produce condensation on your cold windshield (B) dry air absorbs less energy (no water to absorb it) therefore the heater core is able to heat it up easier.
