2003 Questions for all other cars Aircon switches on, then o

Hi, I have a Seat Leon 2003 1.4l. When the a/c button is pressed in and is lit, the aircon compressor comes on briefly when the car is started from cold/long break. Within two minutes it switches off and blows ambient temp air from outside, switching the a/c button on or off has no effect, although there is a noticeable change in the power of the air but no change in engine note.

I then had the unit recharged by a pro but this had no effect at all. There was no loss of pressure and when the unit was tested later, there was again no loss of pressure or other sign of a leak. When I looked under the bonnet, the compressor was not working and the pipes were not cold. As described before, it will come on only very briefly when the engine is cold, but then cuts off after two minutess or so. If the engine is switched off and restarted immediately, it will not turn back on.

I have been told that unless a diagnostic test can identify the cause of the problem, stripping the unit to test each component will be very expensive, as will be condenser replacement. Is this likely to be fuse, controller, radiator or condenser? Many thanks indeed.