Air conditioner compressor: Device that compresses refrigerant so that the air conditioner can work.
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The AC can cool thanks to a refrigerant. The compressor compresses this gas and boosts is through the pipes to cool the air that flows into the cabin. The compressor is in the engine bay and the accessory belt of the engine moves it. It is the heart of the AC system.
Defrost intermittently working cold then hot and back to cold with noise like a blower or under the hood, It sounds like a compressor. A/c Compressor and defrost is related. I am not sure if it vacuum controlled or electronic controled
I figured out it was the thermostat. The upper house was cold, thus the thermostat was shut,, The noise that sounded like a blower,, was the fan on the truck. Turns out it is a very intelligent system , The truck has a brain, that when the thermostat is stuck and senses the truck engine is hot,,, it does all it can to put all efforts to cool the engine. Thus it increase fan speed to a very high speed and shuts down all demands to the cab,,. It shuts down the defrost to conserve energy and to protect the engine... a good thing... I learned a lot and I hope this helps the next person... I am used to old school V8's that you tune by ear. This was a real cool lesson, no pun intended :). I feel very good about the technology our cars have built in them. Mahalo,, Thank you