As of yesterday the fan on my heater/air conditioner only turns on in the high setting. All of the other settings are dead. Not a crisis but it sure is a pain to either have no heat or way to much with nothing in the middle. Looking for ideas. This is on a 99 2500 4WD. Thanks

 

replace the switch

 

Look at the resistor, its not shown in a lot of books as a rule. This has been an ongoing issue with dodge trucks. Many people have replaced the blower motor and or switch and ended up having to replace the resistor only.

 

So where do I find the resister?

 

Am not 100% sure, some are on pass sied firewall in engine compartment some are under the dash in the area of the glove box. it had male plug pins on one side, a bakelite board and them several wound bare wires on the other side simular in looks to the choke coils older mopar gas cars.......

 

The resistor block is screwed into the bottom of the heater box, beside the blower motor. You can see it if you stick your head under the dash on the passenger side. When you remove it, it looks like a rectangular ceramic block.