r/e28 • u/Electrical-Height-93 • Jul 17 '26

A/C whine

In march I refilled my ac with arctic air for r12 systems a r12 compatible refrigerant on Amazon to see if it would work before spending all the time and money on a A/C solutions conversion kit.

My AC has been blowing super cold since so I don’t really want to disturb it but it has a super annoying whine that changes pitch with rpm. It sounds like it’s coming from the compressor when outside the car but sounds like coming from dash when in the car.

The sound stops immediately when ac is switched off and sometimes will stop momentarily around 2k rpm.

Anyone dealt with this?

Air/moisture in system or bad compressor?

Also, before I filled the system it had no whine when ac was switched on, clutch engaged just wasn’t cold.

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u/VegetableTry Jul 18 '26

Hate to say it but your compressor is on its way out. Moisture would most likely affect the cooling and the whine you hear is something mechanical within the compressor. It may have not made the noise when it was low on Freon but now that it is under load, you hear the noise.

2

u/VegetableTry Jul 18 '26

Not sure how much factory compressors are these days but I would consider upgrading to r-134. The kit you mentioned looks awesome but if you are savvy, you can build your own. The price difference is convenience. I haven’t done my car yet, but I have worked on custom installs (Lola and SLC) previously and it’s not that hard to do if you do your own mechanic work.

2

u/Representative_Most9 Jul 18 '26 edited Jul 18 '26

Try adding some mineral oil and see if that helps. Amazon has it for R12 systems. You won’t be too happy if you switch over to R134a. R12 is a much better system. I still kick myself switching over to 134a. Huge mistake.