About Van Expertise I can answer most questions concerning 4X4 engine, drive line, suspension, electrical, and fuel, both diesel and gasoline.
Ford, GM, and Dodge, old and new.
Experience I have been maintaining a fleet of approximately 55 light, medium and heavy vehicles for over 20 years. Most are 4X4 pickups and off road fire fighting trucks. Some vans, wagons, sport utility, and personnel transport vehicles. Diesel and gas. Major and minor repairs due to extremely severe duty.
Question 1992 Buick Lesabre has intermittent heater/AC blower fault. All speeds either work or don't, you never know until you turn the blower on. When the blower will not operate, there is no power going to the blower motor at the harness disconnect. I replaced heater relay (purple wire), this did not fix issue. Turning on the rear window defroster, seemed to start this problem, but it could be coincidence.
Anything else upstream of the blower motor besides the switch could be causing this? I've read about a BLOWER MOTOR CONTROL MODULE (PCM). Not sure this is upstream and could be causing the problem.
Answer Hi Tom,
I would lean toward the switch, although the module is definately a possibility. I have seen that in trucks, and often it can be corrected by unplugging it and then reconnecting it, which indicates dirty contacts.
But start at the switch, and see if there is power beyond it.
