it is probably the bearings going out in the ac compressor pulley or belt slippage. the reason it is different when it is on is because the belt is not under "load" or has resistance.
The ac compressorThe ac compressor
It is on the top of the ac compressor.It is on the top of the ac compressor.
Tighten the belt. The belt drive the AC compressor. On some cars the compressor engages when the defrost is on to remove moisture from the air before it's heated for the defrosters.
Most likely the new pulley is not in line with the rest.
chevrolet and other GM use the HR100T AC compressor
New AC compressor for my 93 Ranger was $156.
Location ac compressor relay 940 volvo
can you bypass a 2001 oldsmobile aurora ac compressor?
my ac compressor is bad and i want to change it myself how can i do this
7 ounces
An AC compressor is part of an air conditioner which may be used in a car's AC system. The compressor is used to change the pressure between the AC's compartments in order to help condense the refrigerant gas back into a liquid.
The AC is a "system", not a single component, and as such, there are parts of the AC system in several areas of the vehicle. The AC compressor is on the engine and receives it's power from the serpentine belt. The AC clutch is on the compressor, enabling the compressor to be disengaged from the serpentine belt when the compressor is not needed. The AC evaporator is a coil that 's inside the heater box, under the dashboard. The AC condenser is in front of the engine radiator. The AC receiver/dryer is under the hood, attached to the firewall. And the AC refrigerant hoses connect everything together.