AC problems. Confused!

[GaryC]

Hi guys. Newbie here! hoping you can help with an issue I have.


2004 BMW X5 3.0i.


AC blows super cold when moving, but when stationary the AC blows warm.



If I start the car up, at idle, turn AC on it clicks in blows cold, fan kicks in but then it turns off shortly after. If you rev it up, it will kick back in.


I have replaced the fan as originally I thought it was that, I tried testing it but obivously as it is PWM (which I didnt know), I thought my original wasnt working. Turns out it worked fine.


Enough gas in the car, have had it vac and gassed twice to ensure and it is loosing now gas, no leaks.


Put a new pressure switch in.


Anyone have any ideas?



Many thanks!

[upallnight]

Verify that the electric fan is coming on when the car is at idle or when you notice that the air is no longer cool or cold. Heat in the condenser needs to be removed in order for the AC to work properly, with the car at speed air rushing through the condenser is enough to remove the latent heat. When the car is moving in stop and go traffic or stopped, the electrical fan must be operating in order to remove the heat that is in the condenser.

[GaryC]

Hi. Yes fan works at idle. As said the compressor will work at idle for a moment (with the aux fan working) but then the compressor clicks off and the fan stops.

Something on the car is telling it to shut down but not sure what or why.

If you rev ot up it will click back in and fan will come on.

[upallnight]

You need to connect a set of gauges to the system to determine the pressure on the high side and low side of the system. This is the proper and really only way to determine what is the problem with the AC system.

[audiophool]

There's also an engine driven fan on the water pump which should give airflow when its clutch locks up. Mine doesn't seem to be working and is covered with oil/dust. Probably needs a new one.

[GaryC]

The viscous fan? Thats working perfect. Checked that as I recently did the oil filter housing gasket so had to come off.


The AC pressure when working reads 10bar on the high side and 2 bar on low, so pretty much perfect. Then when it clicks off the pressures equilize and go to about 3-4bar on the high and low.

[upallnight]

When the AC is not blowing cold air out the vent, stop and open the hood and see if the compressor is still engaged. AC won't work if the compressor is not engaged. See my reply to another member regarding the clutch plate and pulley air gap.