Join Date: Jun 2005
Location: Fir Tree County Durham
Sounds like the same problem as I have, which I have yet to solve.
Get someone to press the air con on button while you have the bonnet open and listen for the commpressor kicking in, you can't miss it its a loud click. If it clicks then its working...
If it doesn't click I would get your aircon guys, if you can't do it yourself, to manually switch the aircon on at the pressure switch to see if the commpressor engages.
It could be a faulty pressure switch, or a lose wire from the ECU to the pressure switch. Or an ECU problem.
Does your internal temp sensor work? To test, stick the fans on Auto. Then set the temp to say 17-18..the fans should kick up a gear. Then turn the temp up to just below max (on a cooler day in your case) and they should slow down.