Depending upon the A/C features in the Subaru - there were a number of different relay arrangements for controlling the fans - but basically the situation was as follows (I think): 1) NO A/C - only main rad fan came on via the Main Fan relay (controlled by ECU D17) 2) Manual A/C - main rad fan came on via the Main Fan relay (controlled by ECU D17) and when A/C was turned on the Sub Fane would also be controlled by the Main Fan Relay. 3) With a fully automatic A/C system - main rad fan came on via the Main Fan relay (controlled by ECU D17) but the sub fan and fan speed was controlled by yhe A/C system. I hope this is close to what went on. As for the ECU signals that are related to the A/C system there are: a) ECU pin D22 - is an output that controlled the A/C cutout relay - to reduce load on engine under certain conditions. b) ECU pin C9 - is the input to the ECU telling it the A/C compressor is engaged and increases idle speed. FROM TOM SHIELS 1) ECU pin C9 (Bl/Rd) is wired to the A/C clutch connector pin 1 (Yl/Gn) and also out to the VW Black box to pick-up the VW compressor clutch wire. If you A/C compressor nas a three pin connector the other