heater blower switch burns often

[Rawze]

(12-02-2018 )alborz Wrote:  2010 Peterbilt 387
The heater blower switch which you change the speed of blower by turning it burns very often and the wire harness that plug into it discolored .
The blower resistor was replaced about two years ago.
Anyone has any idea or similar experience to share will be appreciated.

Possible causes...

* The blower motor draweing too much current.

* The blower is not moving enough air, then overheating, then pulling too much current due to clogging of the core(s), filter clogged, or blower turbine slipping, etc.

* The fuses for the circuit have poor contact, allowing the voltage through to the circuit to drop, and the controller is trying to make it draw more current to speed it back up.

* The blower has been replaced with a higher current model.

Just some thoughts on it any ways.