We have a 96 deville with a north star we put a new ac compressor on and had a local shop put the orifice tube in and charge system. Everything was ok for a week my son was driving and the fan was blowing on high then it just stopped and that night we noticed the interior lights were not working. The code said it was a short in the interior lights. We checked for a short everything ok. We changed the pzm module made no difference. We are able to make the code come and go by turning the headlight switch interior lights from dim to on. We replaced the headlight switch the whole module still the same problem does anyone have any ideas. The blower motor has has 3 wires we un pluged it to see if the lights would work still nothing. Is there a way to check the motor by jumping it?

 

We found the problem. There is a fuse panel under the plastic cover on the drivers side fuses in the engine compartment. the 50 amp fuse was blown for the fan motor. We replaced it. It blew again the fan motor was shorted when we checked it with a meter. With the fuse blown the interior lights would not work. Replaced the fan motor with a redesigned one with the shield on it from a junk yard put in a new fuse everything started working correctly. Why this fuse had anything to do with the interior lights is still a mystery.

 

I am having the same problem...I open the door and no interior lights or blower fan...I checked all fuses under the cover and all are good...the owners manual does not even list the blower fan, how can engineers miss this?...I know the 2 are related just like your situation...but I am thinking that the blower motor is got a open circuit which is why the interior lights don't work either.

Anyone got any clues?