Automotive Air Conditioning Information Forum

Hi all,

Recently changed my car's AC compressor clutch bearing. All went week & afterwards cooling was perfect for only 3 days.
Now the cooling has reduced to a very low level.

Here are my observations;
Outside temp = 32 C
When idling @ 750 RPM low = 75 PSI HIGH = 170 PSI, Interior temp = 27 C
1500 RPM LOW = 55 HIGH = 180 Interior temp = 26 C
2000 rpm low = 45 high = 200 Int temp = 25.5 C

With a card board inserted in front of AC fans, to cover air flow

2000 RPM LOW = 45 HIGH = 210 Int temp 24 C

Your advise appreciated.

Oops. Forgot add.
My car is BMW 525TDS with ND 10PA17 compressor.

Also, noted that with AC off, after about few minutes LOW = 120 PSI & HIGH = 120 PSI.

What year?

It's 1996 june.

No listing in the US for that vehicle. If an expansion valve system. Your low side pressures are high.

Yes, it's an expansion valve system. What could be the reason/s to have high low side / low high side pressures?

Is this an original R134a vehicle? Charge levels is a place to start. Possible restriction but unlucky. Normal expansion valve systems will have a low of around 12/18 at high RPM.

Yes it's original system came with the car.
Can it be the clutch not engaging properly? Before this issue, on & off the belt slipping screeches were heard but not continuously. But cooling was not affected. Now it's not making such noises & the belt is fairly new.
The ratio you mention, is it low/high pressures or temp/pressure ratio?

On some AC clutches, the gap becomes too large and and will not engage; can be reduced by removing a thin shim.

You are head-on.
Removed one of the shims and cooling back to normal.

Thanks.