Stubborn VW Eurovan AC problem

What should I do? I am on my second AC Compressor and it still doesn’t work. My usual independent shop says the new compressor is faulty because it isn’t moving the freon and the parts store says that because the in and out pressure are correct it must be the evaporator core that is broken. I don’t really know enough about cars to know who is right. What now?

Can you tell us the high and low pressures that you got from the parts store and the ambeiant tempeture? I have a feeling that if this car has it you might have a clogged orfice/filter. It is a very cheap part but your A/C system will have to be evacuated to be able to install it. Then the system will need to be vaccumed down and new oil and refrigerant put in.

when the car is running and the ac is on the pressure doesn’t change from the turned off pressure - it is 85 on the low side and 100 on the high. The outside temperature is 82 degrees. I know that they cleaned out the AC several times.

I am not that familiar with the VW A/C system so bear with me. Does this system have an expansion valve leading into the evaporator (inside the van)? Does this van have two evaporator units? Has your mechanic been able to clamp off the liquid line(s) going to the expansion device(s)?

With the pressures you relate, either the compressor output is leaking vapor back to the input side or the vapor is just passing through the condensor, receiver/dryer, expansion device, and evaporator. The second possibility could be eliminated by pinching off the flow with the gauges attached. If the outlet pressure rises, the input pressure drops, and the pressures hold when the clutch is released, the compressor is working. If you still get virtually the same pressure on both sides of the compressor, something is holding the valves open – debris?

Hope this helps. Get back if you think we can help you more.

Hope you are still monitoring this post. I had a chance to research the VW Eurovan A/C system and found a few items that are of interest. It appears that the service valves (taps) are close to the expansion valve. I am accustomed to the service taps being on the compressor fittings. Also the receiver dryer looks different than I have seen them on other vehicles and your van does not appear to have a rear evaporator.

With the taps at that location, any restriction of flow between the compressor output and the high pressure service tap would cause the symptoms you describe. Try this test. With the system charged and the compressor running, feel the plumbing from the high pressure tap back to the compressor. Therefore, you track back the liquid line, to the receiver/dryer, to the sight window, to the condensor, along the face of the condensor, to the hose back to the compressor output fitting. If any of these components are cold or showing frost on the outside, the junction between the warm part of the system and the cold part will have a restriction that flows less than the expansion valve. That is where your problem is going to lie.

In a working system, the temperature should be high from the compressor to the expansion valve and cold or cool from the expansion valve to the compressor suction fitting.

Hope that helps.

Your parts store is dead wrong. The low side is too high and the high side is too low and some more info would help.

Is the compressor clutch actually engaging?
Are those pressures taken immeidately after the A/C or engine has been turned off?

Who did the work?
System evacuated?
How many cans of refrigerant used?