Blower Speeds

I own a 1999 GMC Sierra 2500 pick up. The blower motor switch has 5 speeds and only the last 3 work. Could this be a fuse,or switch or blower motor

Probably a bad fan motor resistor. The fan motor should also be considered for replacement if it’s the original.
A worn out fan motor will draw far more current than a new or low-use fan motor and this additional current (or heat) can contribute to resistor failure.

The fan motor current could be checked with an ammeter if necessary.

This happened to my Silverado. It is likely the resister block. Each fan speed uses a different size resister, and the reisters that control the speeds that aren’t working have gone bad. You need to replace the entire block. It is available on the Internet at a few places, and also at the dealer. If I remember correctly, the part costs about $45 at the dealer.

The resister block is located on the air duct under the dash on the passenger side. You have to remove the cover panel (the hardest part of the job). The resister block has a snap plug with several wires running from it. Unplug it, take out the old block (two screws), and install the new one. While you are under there, you may want to change the cabin air filters while you have the panel off.

The new part from the dealer seems to be made better than the old one, so hopefully this won’t happen again.

if you dont change it eventually the last three speeds will die out one by one, leaving just the high speed fan only.

the resistor is the thing to change.

Unfortuneatley this is typical for GM products: little things like this will nickel and dime you to death. Trade the heap in for a Ford - you wont regret it. But, I’m about %80 sure the problem is the heater motor resistor. You can probably replace it yourself.

My experience is just the opposite. I’ve owned 3 Fords and 5 GMs. I had far more problems with the Fords than GMs.

Uh-huh, it’s just Beefy’s way of thinkin’ is all.