Cananyone help? I have a 964 type 911 1991. It started as an intermittent fault - I would turn on the ignition and all the fans in the car, (ie, heat exchange fan in engine compartment, dashborad fan and oil cooler fan) would all come on full blast. The dashboard fan could not be controlled by the variable dial on the daash. Also the air conditioning would come on.

Turning the ignition off does not stop the fans. This can only be done by removing the fuse No 1.

After a couple of years this intermittent fault has become a permanent fault. In the winter I disconnected the air conditioning pump to save me freezing but now, in the summer, with fuse No 1 removed, I have an unbelievable amount of hot air coming in to the cab. I have checked/changed relays R4 and R14 and also the relay in the enginer compartment. Also I have tried a different front panel in the heater control unit, but no success.

Any ideas? It's driving me mad!