Q: Lately, there has been a really loud humming noise coming from the AC unit of my RX 300. It goes away after a few minutes or if I turn on the defrost. Also if the AC is on when I start the car there is a squicking belt sound that goes away as soon as I turn off the AC.Does anyone have an idea what this might be from?
A: Actually sounds like you have two issues. 1st - Humming sound could be from the blower motor. Remove and check for dirt and leaves in the housing or fan blades. 2nd - Inspect your fan belt, it could be glazed and need replacing. Does the system blow cold? If not the worst case scenario is the A/C compressor is locked frozen or the clutch is worn out.