Fan Switch on the Fritz

I have a 05 Dodge 2500. When I go to turn on the A/C the fan only works in the highest setting. What happened to this part?

Probably nothing. It’s most likely the resistor block.

So How would I repair it?

While I don’t know the specifics for your truck, this is usually a very simple job. The resistor block will be sticking into the HVAC airbox under the dash or possibly under the hood. It will be held in with 2 fasteners and have a 4- or 5 wire electrical connector. If you buy the replacement, just look for the matching part on your truck.

Haynes manuals identify the resistor block locations.

Well, I was looking for the resistor under the glove compartment and I find a plug disconnected. I plug it in and my fan works! If you did not tell me where to look I would not have found the disconnected plug and would have paid the dealer two hundred bucks to find the problem. Thanks!