Guys, I have an old 1998 A6 avant 1.9TDI with nearly 150k miles on the clock, that has been a joy to have, however I now have an aircon problem. The system is fully gassed with 134A however the AC compressor is not kicking in. I have no schematics of the wiring and am therefore at a loss to do all but the most basic diagnostics (fuse testing). The manual mentions fuses 3, 5, and 15, all of which are good, but I'm surprised the AC clutch isn't mentioned. The thermoelectric fan is also not cutting in, but to be honest the engine runs quite cool most of the time. Are there relays, switches or whatever that I can check that I may have missed before I end up taking it to the money pit that is my local Audi dealer? I am driving down through France this week and the thought of my kids moaning about the heat all the way down..........Any ideas greatly appreciated.

 

Of the various problems in a car air-conditioner, one of the most common is the accumulation of dust and debris in the radiator fins and condensing coils. This leads to a drop in the heat dissipation efficiency of the coils. In turn, the cooling performance is affected, and an overload for the compressor could eventually (since the compressor draws power from the engine) lower engine's power and fuel efficiency. The simple solution to this problem is a regular pressurised water wash of the radiator and coils. At times, the air-conditioner performance also drops during long trips when the evaporator fins get clogged with ice and frost created from moisture in the air..check the audi head gasket for possible leaks..