A/C Compressor Howl

highmiles · Post by **highmiles** » 13 Jan 2020, 13:08

Still on the path to having my 2001 S60 T5 5-speed back on the road (purchased it as a timing belt failure car with partially disassembled motor,) and have found one final (I hope...) hurdle.
The car would start OK when cold, but with a howling noise (turbo?, PS pump?, A/C compressor?) that would go away after 5-10 seconds and then run well without noise. However, warm/hot starting was more difficult.
This weekend I hooked the car up to VIDA and manually kicked on the A/C compressor while the car was running, instant stall. I then disconnected the electrical connector at the compressor and found no more howl and easy warm/hot starts. I can only guess that, even with the climate control set to "off," the computer still kicks in the A/C compressor briefly at start up?
So the question of the day is... is there anything to be done to free up the compressor? I assume it has low pressure since it never kicked on even from the climate control system or switching to defrost.
There are plenty available at the pull-a-part, that is my plan for the weekend unless there is magic to perform the one in the car.
Thanks! John
ps. the combination of the 2.3 with high pressure turbo and the manual transmission is a darn quick package!

Post by **abscate** » 13 Jan 2020, 13:20

I can only guess that, even with the climate control set to "off," the computer still kicks in the A/C compressor briefly at start up?

This is one of those deep P2 understanding realms that you have entered

If I recall, the AC in a P2 changed from COTS to the newer type(forgot the acronym) and one of the other changes is it briefly kicks on the compressor at start, to push out any condensed Freon in the condenser from shutdown.

If i got anything really wrong here, jimmy will fix it.

ps. the combination of the 2.3 with high pressure turbo and the manual transmission is a darn quick package!

Laying waste to the BMWs ....especially if you stay in the power range of 2nd and 3rd gear

Post by **oragex** » 13 Jan 2020, 16:10

This is for the clutch bearing and the shims www.youtube.com/watch?v=KAGDkwYSFY4 BUT from what you are describing, I would guess it's rather the compressor itself, maybe overcharged/undercharged or perhaps a faulty expansion valve ?

highmiles · Post by **highmiles** » 14 Jan 2020, 08:46

Thanks for the responses.
I should have hooked up the gauges to it, I will next weekend just to see if it has any pressure in it. Since the car sat for some time I surmise it is locked up mechanically, though the system was left closed the whole time.
Still planning a junk yard run for Saturday...

Post by **RickHaleParker** » 14 Jan 2020, 09:13

abscate wrote: 13 Jan 2020, 13:20 kicks on the compressor at start, to push out any condensed Freon in the condenser from shutdown.

To keep the compressor oil from settling. The compressor oil is part of the sealing. If the compressor oil settles the refrigerant will leak out. This is why cars that have been sitting for a long period of time need a refrigerant recharge when put back on the road.

Post by **abscate** » 14 Jan 2020, 11:19

RickHaleParker wrote: 14 Jan 2020, 09:13
abscate wrote: 13 Jan 2020, 13:20 kicks on the compressor at start, to push out any condensed Freon in the condenser from shutdown.
To keep the compressor oil from settling. The compressor oil is part of the sealing. If the compressor oil settles the refrigerant will leak out. This is why cars that have been sitting for a long period of time need a refrigerant recharge when put back on the road.

Indeed, Freon isnt going to condense in a system shut down at any normal temperature. Oil it is.