I have a '08 Audi A3.
A month ago I noticed that the air conditioning was performing poorly and since I bought it used, I took it in to recharge the refrigerant, without any improvement.
When the car is in neutral, idling or revving a bit, the A/C fan starts working, and in a couple of minutes I have cold air blowing from the vents, as long as the gear stays in neutral. Using a mercury thermometer, the middle vent temp was around 8-10 C.
However, when the car is driven, the A/C stops blowing cold air instantly, until it goes back to idling. There is no indication on the dashboard that the A/C stopped working or is working on safe mode (or econ), like other cars do.
The mechanic could not find any pending fault codes.
This time we noticed that half of the refrigerant was lost, the low-side pressure was at 3, high-side was at 14 with an outside temperature of 26 C.
We recharged again the system with a UV leak detection kit. There are no leaks visible and I cleaned the AC radiator from the outside.
What could be wrong?