blower

[gregjo1948]

2001 Ram 2500 4x4 Diesel 5 speed manual----Heater/ac blower only runs on the highest setting. The heat and ac work as they should but, the only fan/blower setting that works is the highest. Do I need to install a new blower/fan switch or, is there something else that would cause this problem? thank you, gregjo1948

 

[DodgeTx]

sounds to me like the switch is malfunctioning, however a blower fan is only $25 online. Might be worth trying that first?

 

[Mop]

Sounds like the fan Resistor might need replacement. It's under the dash, near the floor.
A little tight to get to, but it's just 2 screws and a wire harness.

 

[MarineBSP]

Mop's got it.

You'll want to test your motor, of course. Apply direct battery power, and if it runs at full speed it's probably okay. The way most manufacturers run blower fans is with a "resistor pack" of varying degrees of sophistication. The highest speed is low (or no) resistor, and as the resistance increases in series with the blower, the speed goes down. These resistors get very hot, the cooling fins for their heat sinks get dirty, and the resistor packs die - the classic symptoms are full speed only or no fan at all.

I see you have a 2001. If your truck has lots of miles and you live North, consider a new blower motor or re-brushing the old one before winter. It's no fun to be without heat and defrost in the winter.