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 guess would be a broken mode door in the hvac case...

 

heatertreater.net

Do some reading on that website and see if it helps diagnosis..
I just purchased their setup for my truck..

 

Thanks! I will check it out can I replace myself?

 

To remove and disassemble the HVAC case the dash has to come out, coolant drained and AC system evacuated. I had the dash and HVAC unit out on mine, and paid a couple hundred to have the AC system evacuated and refilled by an AC shop.

Not a big job, but time consuming.

Heater Treater has metal replacement doors and a plan for cutting the HVAC case to be able to replace the doors w/o removing the dash and HVAC case.

See also this thread, and the thread it links to.

https://www.dieseltruckresource.com/...d.php?t=210483

 

How much to have someone do all the work? So I guess the heater control is not to blame? How can I test the system to narrow it down for sure?
Thanks

 

I'm not sure how you would determine for sure if it was a control issue or a mechanical failure in the HVAC box... other than maybe watching the actuators move when you change settings.

I would guess a dealer would charge $1200 or better to do anything involving removal of the HVAC case. Just a guess. Not complicated, but time consuming.

 

My 2003 had exactly that problem; I finally broke down and took it to the dealer and they took it all apart, put in the plastic flap, and put it back together. I think the bill was about $500.00 but my feet are warm now. Good Luck.

 

Go to heatertreater.net site and read the troubleshooting section... It has really basic steps for determining whats wrong without taking it all apart.