Jim @ EuroWerks

Who knows what pressure or temp the condensor fan is supposed to kick on on an 85 928?

WallyP

On the pre-S4 cars, the A/C turns the electric fan on by means of a temp switch on a stalk on the receiver/dryer. The heat from the refirgerant is transmitted thru the sealed stalk by metal contact. No idea of what the trigger temp is - but it doesn't work well, in my opinion...

I would seriously consider solving two problems at once. Get a good continuous-duty 12 vdc relay (they used to be sold as "headlight relays") and install it on the right fender panel. Hook the A/C compressor clutch wire to the trigger of the relay; a fused heavy power lead from the jump start terminal to the relay input; a heavy wire to the compressor clutch; and a heavy lead with a blocking diode to the electric fan.

Now the fan runs any time that the compressor does, the normal radiator temp control and intake temp controls on the fan still work as before, and the little blue relay in the A/C controller should last a lot longer.

Jim @ EuroWerks

Wally, I deffinately agree. While I was gone, I ck'ed schematics and you are correct. It is the temp switch at the top of the drier. On a day like today 65F ? I'm seeing high pressure side stuggling to hit 300 psi but it will do it. No fan at 300psi this concerns me.

Jim @ EuroWerks

I jumped out the temp switch and the fan works. So, I know that the rest of the circuit is working fine.