1989 Cadillac Fleetwood Defroster vents run after car is of

GARION

MEMBER
1989 CADILLAC FLEETWOOD

Air Conditioning problem
1989 Cadillac Fleetwood

My mother recently spent $2000 on two trips to the dealer to fix her air conditioning. First it was a temporary fix, then they had to replace the unit ( I think it may have been using the old Freon or whatever ).

It worked fine there for a short time, but today when she turned it off, air continue to blow out of the defroster vents (the ones inside and out of the window). It doesn't run at full power (as when you turn on the defroster when the car is started), but it continues to run.

I finally got it off after turning the car on, pressing the defroster button, then low fan, then off, and turning off the car. It worked twice, but I don't know if it always will.

She also didn't even turn on the defroster (or the AC, I think), but it still did it when she stopped the car.

I wonder what could cause this. Would it be a fuse or an electrical/computer thing or? I really don't want to have her take it back and waste another ridiculous amount of money for this (I mean, she has put more in it now than the thing is worth), but I don't know really what to look for myself.

Any help would be appreciated.

1 Reply

FACTORYJACK

MECHANIC
4,159 POSTS

There is an A/C power module on the HVAC case under the hood at the firewall. It may be under a plastic cover if the cover is still there. Under about the center, under the maxi-fuses/relays you'll find it. Two connectors, one four wire, one two. There is large red and black wires on the two wire side, when the blower is running with the key off, disconnect that, then replace the module, it is shorted. The fact it is coming from defrost, may be result of default after loss of engine vacuum, which is what that system ran on for mode functions. This is for a FWD fleetwood, not RWD.