prescott

My 88 928 manual cooling fans run on cold start up (car has sat for 3 days unused, temp in the garage is 40 degrees). It has done this (off and on) since I had the intake manifold off for a leaking coolant bridge/thermostat housing. It has "burped" air into the overflow tank and has required 1 L of R/O water. Air conditioning button is in the off position. I cycled it on and off several times, no effect. This morning when I started and it did this and the tank was full of water....no coolant leaks. After driving to my office and parking and the car was at temperature, the fans were off.

Other work that has been done after this problem surfaced and that is probably non-contributory but for the sake of thoroughness. Radio head unit was recently installed and works correctly. New digital clock replaced old unit. Cruise control brain was disconnected from the 14 pin and removed. Currently the car has no cruise box in place (shouldn't need it right?).

Any ideas about what is causing the fans to be on on cold start?

Brian

PHIL928

Not sure if it's the same on an '88 but make sure the AC is completely off, ie slider all the way to the left.

GlenL

Defective radiator thermostat.

prescott

Thanks for you comments.

Thermastat was replaced when we had the coolant bridge off recently. The car certainly isn't running hot (bottom third of the temp range).

Got out of work yesterday and found a pool of coolant under the passenger side wheel (figures!). Looked around with a flashlight and there was a small amount of coolant on the outside of the plastic. Looks like a coolant reservoir crack or the cap is leaking.

I've read this is a PITA to replace. I'll order all the hoses and parts from Roger.

Hope this fixes the problem.

GlenL

I'm sorry. What I meant was the temperature switch in the radiator.
P/N 928 606 149 00

You could try disconnecting the wires to it and see if that prevents the fans from coming on.

Alan

As above - are you sure the AC is really off (check @ the freeze switch) It is not only the AC switch that turns it on...

Alan

prescott

Ill check that

GregBBRD

Almost always the temperature switch on the top of the intake manifold. Open the hood and see if the fans go off. Wiggle the sensor around and see what happens.