Hi all, more of a motorcycle guy so I'm pretty bad with car stuff (not that I'm mechanically inclined anyway). I have a '97 Honda Civic. Until I let my car sit for about a week/ 2 weeks, when I had the ac turned on, I used to hear a violent (literally) clunking and loud screeching sound until I started accelerating. The clunking stopped but the screeching continued until about 15-20mph. At that point both noises were gone. I no longer get the clunking (at least not as noticeably) and a slight screeching when stoppedwhich I suspect is maybe the belts? If I turn off the ac the noise goes away. What is causing this? My ac doesn't seem to be as efficient at cooling the car as it used to be either. Thank you for your help

 

get some belt dressing first to eliminate you belt noise then see if noise is from AC pump, maybe the AC clutch on the pump is bad..

 

Make sure that the condenser fan works. The condenser is the radiator-like unit to the left of the radiator. It's fan should be on any time the compressor is engaged. If the fan is OK you would need to tighten or replace the compressor belt.