2010 Q5 AC Compressor (new) Noise

[Wowndeye]

Hey guys...

I've got what sounds like trouble with a new ac compressor. Watch/listen here: https://youtube.com/shorts/Xaw_oIUOXYs?feature=share

I just got finished replacing the ac compressor and condenser on my 2010 Q5 3.2. The original compressor belt pulley broke so I pulled it and the condenser, flushed the evaporator and just got it all back together.

The compressor was from RockAuto and is the UAC model they had for my car. It came precharged with 5.7 oz of oil.

My process was this:

After removing parts, I used ac flush to clean the evaporator via high pressure line.

Ran compressed air via air compressor through high pressure line till almost nothing came out. (was very clean)

Upon opening the compressor box, I set it up vertically for a few minutes and then spun the pully clockwise 10x like I saw recommended. Then repeated it a few more times just to be sure the shaft seal was lubed.

Next, hoses were attached and it was mounted back on the block.

New condenser was installed w/ drier already installed.

All ac connections were made and then put the rest of the front end back together.

Pulled vacuum for approx 2 hours and then let sit for an hour to check for leaks. No leaks...

(I was going to wait till this weekend to put R134 in due to current weather and wanting to do it during the daylight.)

I started it up after putting the serpentine belt back on and it all sounded fine till I took it out of the driveway and it hit close to 2000 rpm's. That's when I first heard the noise.

Slowed down and sped up a little and it kept happening and didn't change so turned around and drove under 15 mph back to driveway.

Could I have a bad replacement compressor?

Does anything sounds wrong about my flush/install?

I saw another video that made it sound like you spine the compressor about 10-20x before pulling vacuum or charging the system to prevent hydrolock of the oil in the compressor. Could that be the issue? I hadn't spun it once installed, prior to pulling vacuum.

Could it be that I haven't added the R134 to the system?

Or any other thoughts on what I might be missing?

I really want my car back!!!

Thank you!

[StuckAntichris]

Seems like a silly question but you did not have the AC on while you were driving did you?

Also it is possible that you got a bad compressor but unlikely. Verify that all spinning components spin free and without noise by spinning them with your hand without a belt installed. Check your belt tensioner, alternator, any idler pulleys and lastly your compressor. If it was making noise you will most likely feel a bad bearing.

It also might be worth putting the 134a in if you find the compressor spins by hand. Could be some weird issue with the vacuum.

[Turbo510]

I don't think that it's possible to hydrolock the compressor due to the one-way reed valves that compressors typically have. However, I would certainly add the refrigerant before running again. The swash plate's movement relies on gas pressure I believe, plus the flow of gas is what distributes the oil.

Last summer we changed the compressor on my son's 2009 3.2 Q5 (used to be wife's until she got an '18 Q5). We got it done in one day at my son's Air Force base auto shop near Phoenix, in 115 degree heat no less. You were more thorough than we were; just crossed our fingers and skipped the flush and new drier, bit did do a long vacuum as you did and no leaks either.

[Wowndeye]

Thank you both for the replies!

I figured it out though yesterday morning... I initially pulled the pressure switch off the condenser to see if that made any change which it didn't. Then I simply released the vacuum from the system and the sound was gone. Took it for a test drive and it was all good. Drove it to/from work and all was good. I'm adding refrigerant this weekend. I don't understand the guts of an AC compressor but seems the vacuum was causing something to make some noise. Just hoping I didn't do any damage that will cause premature failure.

To answer the earlier questions... The AC was not on when I was driving. When I had got back in the driveway, I did tap the accelerator to see if it made the noise when parked and did when the engine hit about 2000 rpms again. I hit the AC switch just out of curiosity and there was no change.

Odd thing is that it looks like the compressor was engaged because both the outer and inner parts of the compressor were spinning. This compressor's clutch looks different from others I've seen so not sure what normal looks like for this one.

I haven't had a chance to change the idler pully or tensioner but have them and am ready to do so. At first glance, I couldn't see how to pull the originals off and I didn't have the torque specs so just moved forward for the time being. Just replaced the alternator a month prior to the AC compressor going out and it sounds good.

@Turbo510 - I found your writeup on your swap which was very helpful. Looking at the rear compressor bolt in the back was intimidating and looked near impossible but the 3/8" swivel was the ticket! It was nice having a heads up on that power steering line.

In the end, it's not that bad of a job to do, it's just more surgery on the car than I would prefer and a little tight and awkward at points.

Thank you again guys!

[Turbo510]

A couple of points: I would really not be comfortable running the car without a refrigerant charge, due to the lubrication issue. Also, this compressor has no clutch; the insides are always moving when the engine is running. It uses a variable-stroke arrangement to regulate the pressure across the orifice at the evaporator (the part that gets cold). Another question: when you "released the vacuum" that meant you let air in - am I correct? That would mean redoing the vacuum step to get air and moisture out.

[Wowndeye]

Thank you again for the input! I wasn't sure about the mechanics of the compressor and made the assumption that people likely drive around unknowingly without a charge in their systems due to a leak, and again I'm assuming they do so without any major consequences. I had a couple vehicles in the past before I started working on cars, that were like that and they never gave me any further trouble.

I have been working on this outdoors in a gravel driveway in the Pacific NW and rain/wind had been coming and going at various intensities and so I was working hard to get the car back together because it had been sitting for about 5-6 weeks till I could make sure I had done most of my homework before diving into the project. I was in a hurry to get back in it so was initially going to wait till a nice, clear, relaxed day to do the charge but I had talked with someone else who knows cars far better than I do, late last week and he had encouraged not driving till it was charged as well.

When I did release the vacuum, yes, I let air in. I did though do another long run with the vacuum before charging the system with refrigerant yesterday.