I have a 06 3500 with dual heater controls. I have a question when I have it on defrost it comes out of the defrost when I switch it to floor or panel it seems like Im not getting the full force of the fan coming out of these areas it almost sounds like some of the air is still going into the defrost. One person says my heater control is bad and I need to spend $275 for a new one part # 55056570AD Does anyone know what is going on. I pulled the heater control out and it has a date of 10/20/08 well my truck is a 06 so apparantly this has been replaced once already but no one can find this number. I hate to spend the money if thats not the problem. Any help would be apprieciated. Thanks

 

My problem is just the opposite, won't defrost, and a quick search turned up al sorts of issues on this. I was looking for a STICKY link. crossy

 

you can watch the motor turn from the gas pedal area,

and if the motor is turning, you need to do the heater treater doors.

this thread is about how the white teflon/nylon insert stripped out AFTER heater treater doors.

but this shows which motor it is:

https://www.dieseltruckresource.com/...r-t281733.html