Hi, can anyone help me with a problem I have with my air conditioning, when I start a journey my air conditioning works perfectly and for as long as the journey lasts, no matter the time or distance. As soon as I stop and then restart the engine the air conditioning blows warm, if I keep switching the air conditioning on and off it will eventually restart, sometimes quite quickly and sometimes it takes a long time, when it does come back on it works perfectly. Any advice would be greatly appreciated.

When your aircon is on and blowing warm check the pulley to see if the clutch is engaging, other common culprit could be a tired solenoid on the pump, these can be replaced separately on many models 

Hi thanks for your reply, I will google how to replace the solenoid and check if the clutch is engaging.

With the aircon turned on the aircon pulley has a centre section of the pulley that is controlled by a electronic clutch, it will operate for 20-30 seconds then disengage for 20-30 seconds, you will here a click when the clutch kicks in

Hi, thanks for your advice, I don’t think it’s the clutch, I’m going to get the solenoid checked out, I’ll post and let you know the results.

The clutch’s are pretty reliable 

When was the last time you got it recharged, you might be right on the limit of ac pressure sensor shutting down the system, remember the system turns from liquid into Gas and back again so a change in pressure is inevitable 

It’s a while since it was recharged, I’ll get that checked as well, thanks again for all your advice, it’s most appreciated.

Took the car for a diagnostic check today, not to an Audi garage, and the fault that was displayed was no communication with the auxiliary heater, would this cause a problem with the air conditioning.

2 types of auxiliary heating available, common was a electric heater that goes inside heater box behind dash that gives some heat until the diesel engines warm up, other option is a diesel heater that keeps the cabin warm when engine is not running, first type is most common and can’t see why this would cause a aircon problem. 

Ideally you need someone who can look and understand the live data readings that a good diagnostics can provide and try to get the fault to occur while doing this to see what changes

Hi, Thanks again for all your advice, going to try and find someone who can read the live data.