Hi the compressor has a device usually a pressure switch that on off loads the head inlet compression valve system. With a screw compressor it is usually a diaphragm operating a piston that open and closes the inlet to the element
why wont the ac compressor shut off stays on on all settings
It is low on freon.
yes
All automotive air conditioner compressors work by going on and off. That is how they control the temperature. If they are mostly off, they make it warmer. If they are mostly on, they make it colder. The fact that it is on an Impala has nothing to do with it. The fact that it is an automobile air conditioner compressor has everything to do with it. Something would be wrong if it was not going on and off.
Compressor will normally run when in defrost mode.
most likely, the ac compressor is not functioning properly. when compressor's speed sensor is not the same with engine speed the ecu will shut off power to compressor. time for new compressor.
A refrigerant compressor will be hot when running whether or not the charge is too high or too low. If the charge is too low, the compressor will cycle on and off. If too high the compressor may not run at all.
The air compressor takes time to shut down fully so it can't stop as soon as Ur veichle has stopped
You are better off replacing entire compressor, then you know all other bearings and parts are good.
Best way to check if the AC compressor is working or not is take off the compressor and take it in to get it tested. Auto Zone, O'Rily or some auto store and they don't charge you at all it's free. The only catch is you have get your lazy butt to do the job cuz there is no other easy way to test the compressor other then getting dirty and spending the time to do the job yourself. Unless you got the money to take it to the shop and get it looked at and pay for all that expenses.
Loud noise is not a good description. If its a loud squeal turn the air conditioner or defroster off. If the squeals goes away the compressor or the clutch for the air conditioner compressor is locked up.
No it is not. But I have heard it could be damaging over time to the A/C compressor to turn off the engine with the A/C on.