Loose connection?
Bad fan motor (windings opening when they get hot)
Loose fuse/relay?
Bad or worn switch?
Bad resistor?
No, the compressor only draws out the heat from air. The blower motor either blows warm air or cold air.
The same as any air conditioner. The process uses compressed gas to chill a screen or vent inside your airducts. A fan then blows through the vent cooling the air temperature as air flows through. Parts of auto A/C include; an engine mounted air compressor, pressure hoses, ducting, a blower/vent box ( usually under the passenger side dash), and a thermostat.
it's a problem with the blower motor resistor
Replace the blower motor also.
If your 03 Trailblazer blows heat out of the back vents when set on AC sometimes, it could be because of a faulty blower motor resistor block.
it blows air
It will be located somewhere in the path of the air that the blower motor blows.
A glass blower is a person that blows glass.
If the heater is blowing the fuse when the blower is turned on, I would suspect the blower motor is defective or locked up. If the A/C is blowing a fuse, suspect a bad clutch, or locked up compressor.
A vehicle air conditioner has two basic components; the compressor, and the fan, or blower. If the compressor is working, the air coming out of the vents will be cold, but if the blower is not working, the air will not come out very fast. Hot wire the blower to the battery, to bypass any fuses or switches, and see if the blower will run. If it does, but will not run when connected normally, check the fuse for the blower. If it is good, you would be wise to take the vehicle to an automotive electrical specialist to have them troubleshoot it.
As for why it blows only on the high speed you most likely will have a bad blower resister and for the noise, it could be a bad blower motor, bad blower wheel or trash that is stuck in the blower wheel or housing.......
Somewhere in the path of the air that the rear blower motor blows