Good morning oldsmobile enthusiasts.

I have a 79 olds regency 98. The switch for the fan on the dash works on all the lower settings but does nothing on the high setting. How do I figure out where the problem is/fix it? Thanks.

 

The problem is usually one of two things. First thing to check is the four wire connector in the harness that runs across the back of the engine near the distributor on the passenger side. There is a heavy red wire in this harness that powers the blower motor relay. The terminal in that connector gets dirty, overheats, and melts the connector body. Pull the connector apart, check the terminals, and clean them if needed. If this connector is good, the problem is almost certainly the blower motor relay, which is used in the high speed position only.