MBMB

My '89 GT has been off the road for what seems like years while I do some behind-the-dash stuff.

I finally got the central electric panel back in and everything hooked up. I switched on the key (but didn't start the car) to test a wire, and after a couple of seconds both radiator fans came on full blast.

Is this normal radiator fan behavior? I don't recall, and if I messed something up with the central electric panel out I want to fix it before I get things buttoned back up too far.

Also, I found that one of the two big red wires going to T24 and T25 for Radiator Fan 1 and 2 had been chopped, and the plug end had been spliced into the other (that is, T24 and T25 are wired to the same big red wire, and the other is hanging loose). So it may be that the car is only switching on one fan, but the other is coming on as well.



The PO made other wiring modifications (to install electronics) that I have returned to stock. This one looks like it might have been done because of a mechanical problem, so I haven't spliced the wires back to original yet.

Any suggestions or comments?

Thanks.

Calgary Ole

Only time the fans would come on is if the AC was activated. Try again with the HVAC in the off position.
If the water temp is not above 83C the fans should not be on.

MBMB

I still haven't reconnected the AC controller.

(Rear AC compressor switch may be on, though. I'll check that tomorrow.

Calgary Ole

I do not have exp. with rear Ac but still, fans should only come on with temp above 83 C or AC activated

Stromius

If the temp sensor on the lower, drivers front of the radiator is not plugged in, the fans will run full blast too.

Tails

This is not normal.

I would suggest that you repair the wiring to correct circuit as contained in the wiring diagram and then follow the fault finding procedure, as shown in the WSM. This procedure will tell you how to test the temperature sensors, and the computer control system.

As previously advised the two fans should come on initially at low speed when the lower temperature setting is reached and if the temperature exceed the high temperature set point the two fans will go to high speed. This is fully explained by the graph in the WSM. The diagram will also show you the when the flaps open to 30% and 100%.

The fans will operate at full speed with the air conditioning on or if the windscreen defrost is selected on the control slider.

Tails 1990 928S4 Auto

Tails 1

TheoJ

maybe check at the controller next to the pass.seat. Plugs are in and the system is powered up properly? The controllers and the power stage up front actually drive the fans. There is no obvious relationship with the dash removal other than what's already been said.
regards
Theo

jon928se

+928

or if that sensor is bad or if the connections to it have corroded.