Air conditioning not working - Passat, 1997

Hello.

"My climate control (Climatronic) has stopped working recently."

I have connected a service station, and the pressure on the low-pressure side reaches the target value of 2 bar after the magnetic coupling is activated. However, the high-pressure side does not increase from the static pressure of approximately 4 bar at an ambient temperature of 15°C; instead, it drops to 2 bar.

After that, I extracted the refrigerant (approximately 900 grams). The suction process didn't proceed normally; instead, after the service station entered the vacuum range and the suction stopped, the pressure in both circuits increased again (almost to the static pressure of 4 bar).

This continued for over 2 hours. (Possible moisture in the system?)

After that, I removed the expansion valve and compared it to another one. The openings of the control piston matched the new valve.
I then detached the hoses from the compressor and manually rotated the compressor. On the pressure side, I was able to build up some pressure. However, I still removed the cover from the compressor and examined the valves. These are also fine, and they don't contain any wood shavings.

I then flushed the pipes again, and I couldn't detect any blockage.

I'm going to replace the dryer now, because I've run out of ideas, and hope that it will then work.

Today I installed a new dryer, evacuated it for 30 minutes, and then refilled it.

Suction pressure drops to approximately 2 bar, high pressure is around 6 bar, and the exhaust temperature is approximately 9 °C.