I have a '90 Park Avenue with the "electronic climate control" option. The other day I had the AC running and the blower fan stopped working. I suspected a blown fuse, checked fuses-all O.K. Took blower motor out-tested O.K. I have replaced relay above blower cabinet, tried a new resistor module in blower cabinet, jumpered fuse link, tried my backup indash control keypad, still cannot get blower working. I am fit to be tied. Any help out there?

Have you probed if any voltage present at the blower motor ?

If you have it may be the motor has a bad ground. Also check if all
contact are'nt oxidized. You may have voltage but almost no ampere if
you have bad contact. Hope it can help

I think it will stop working if the A/C charge gets low. I have a '92 Ultra (which I'm selling) that did that. As I remember, the read-out flashed also.

check voltage at the blower motor plug.

jump the relay if no voltage going to motor.