Automotive Air Conditioning Information Forum

This particular compressor is a clutch-less direct-drive variable-displacement type and doesn't engage and disengage in the traditional sense. It constantly runs whenever the engine is running. It has an electronic control valve that varies the displacement according to system demand.

That said ...

So now, do we suspect the bearing in the compressor?

Right, Noquacks, a belt that's lasted since 2009 and still looks new is either proper good rubber or you've got a very smug garage lol. Spinning the compressor pulley by hand is fair enough, but with the belt off, and with the clutch not ...

Could it be a bad serpentine belt? Compressor starting to go bad (bearings, etc)? Maybe the spring tensioner on the serpentine belt?

If my vehicle, I'd pull the serpentine belt and then spin the tensioner pulley by hand, and feel/listen for an issue with that.

And how old id your serpentine ...

People,

2009 BMW 328i, original owner, 70,000 miles, manual trans. When I shift gears with ac on there is a whining sound that increases with pitch matching the gears I am shifting. The sound matched 100% with the rpm's. But as soon as I turn off the ac button the whining stops.

AC is ice cold ...

It has been on R134a for 20 years. That is not the problem. But good point!

I tightened the belt a bit, actually, to the max setting, which I thought was not a good situation for a belt to tight on the max slider notch. Started the car, and the squeal almost disappeared. But i watched the belt as it turned with ac on, and the upper edge of it was wobbling a distance of say ...

Cusser wrote: Fri Oct 02, 2026 5:51 am

Noquacks wrote: Fri Oct 02, 2026 5:10 am Could it be the loose ac belt needing tightening?

That should be easy enough to check.

I might pull the belt, and check any tensioners and AC clutch pulley bearings for drag or noise. And maybe install a brand new belt.

Thanks, Cusser. Good tips. Will try those checks this weekend!

People,

1987 Sunbird, when I switch on the ac button to activate compressor there is immediately a loud screeching sound from the comp area. It stops after about 7-8 seconds. Vents put out ice cold ac. Then, every about 5 minutes the sound comes back, then again, goes away. Could it be the loose ac ...

People,

I heard that the dust caps are a primary device to prevent gas from escaping from a schrader valve, and not a secondary device (the valve being the primary). Is that true? Sometimes, when I work on my auto ac I unscrew the cap and notice the psssssst. That should mean that the valve is ...

People,

2001 civic EX, original owner. AC blows very cold sometimes, when it does the comp cycles on/off every 3 seconds, so quickly like something is wrong. Then, during a drive, out of the blue it stops blowing cold completely. Pressures on the ow side show 30-50 or so when blowing cold (cycling ...