Rep Power: 0

I have a 04 civic ex 4dr. The belt started squealing about a year or so ago at start up and sometimes on the road even if the AC was not in use (just the cabin). Thinking that the compressor was going out I replaced it with a re-manufactured one i bought on ebay. Got it in and had a local AC/radiator shop do the Freon. I does cool just fine but almost always squeals at startup and many times on the road. It has gotten better but I can't for the life of me figure out why it's squealing. The clutch pulley rotates smoothly without wobbling but it will squeal even if the AC is not being used and the fan is off at start up. All the bolts holding the compressor seem to be tight, the belt is tight with only about a half inch movement at halfway point between pulleys. If I change the belt, the noise will go away for a day at the most and does actually get better with each belt change (purchase belts from dealer) but I am so done with this and getting really frustrated. I have come to the conclusion that the old compressor probably was fine to begin with but the problem is something else. I did change the alternator not long before the compressor and seems to be working normally (was having some electrical issues prior to changing and no longer have those). At start up it will squeal for as short as a few seconds to as long as 30-45 seconds without the AC or cabin fan even being used. Also when idling and the AC is being used the compressor cycles on and off as normal but when it cycles on there is a fair amount of vibration like something is loose but not sure what that could be. Any help would be appreciated.

 
Rep Power: 118

 
Rep Power: 518

PS uses its own belt and there should be minimal load on it unless and until the steering is in use.
Probably needs to be tighter.
AC compressor and alternator share the same belt on this engine. Immediately after startup the alternator is trying to charge at a high rate therefore it places a lot of load on the belt
If you're driving around with the hvac controls set to any of the windshield positions it will run the AC system whenever possible even though there is no light for it on the panel.

Tighten this belt. (Many people just don't get it tight enough to stay quiet, especially old schoolers who were used to the old V belts that didn't need as much tension).
Also note, some belts (especially aftermarket) may stretch with time and miles necessitating occasional readjustments.

 
Rep Power: 0

I’ll have to use a wrench on the thumb screw tensioner to get it any tighter. I forgot to mention that occasionally when I slow down the belt will sqeal as well. I have to turn off the ac to get it to stop but at times when I do this it will sqeal when I make the turn as well (no ac no fan no nothing). If the ac/alternter bracket (more like a steel plate) was loose at all would that cause this problem? I have been buying the belts directly from Honda parts at my nearest dealership.

 
Rep Power: 0