Air conditioning system 93`Audi 80 TDI

Hello everyone,

I'm having a problem with my air conditioning…

Specifically, it's a manual system. When I turn it on, the compressor engages and it noticeably cools.

However, after a while, I start to notice a distinct jerkiness while driving, which occurs approximately every 10-20 seconds. This wasn't happening before.

You can hear a distinct clicking sound, like a relay or switch being turned off in the passenger's footwell, followed by a brief click of a relay in the driver's footwell, and then the compressor engages… and it jolts… and a few seconds later, you hear another click in the passenger's footwell, and the magnetic clutch disengages the compressor. And this happens repeatedly…

Does anyone have any ideas about what might be causing this?

The system was last filled about two years ago.

I've read something about a pressure switch. Does anyone know where it's located?

Best regards

I suspect that the air conditioning unit is repeatedly turning on and off due to the low-pressure switch, which is caused by a lack of refrigerant.
Yes: your manual air conditioning unit is diagnostic, so you can easily check it.