I just bought a 2004.5 2500 CTD and every once in a while if I have HVAC set to vent or a/c and switch to heat or Defrost it won't switch, like the blend door problem. But if I mess with the **** and switch it back and fourth it will switch with some delay. I have turned the fan off then switched from position to position you can hear the actuator motors doing there thing and the different doors moving and stopping and when they stop I turn the fan on its doing what its supposed to do, even recirulate on a/c. I can do this multiple times and it always switches. Its just that once in awhile, but not every time it is stuborn when switching to floor or defrost with the fan on. Could the actuators be getting weak and switch fine with no fan and struggle with the fan on or could the Control head be going bad and not making the switch every time?

 

https://www.dieseltruckresource.com/...d.php?t=111716

I posted to this old thread a day or so back mine seems to be doing the same as yours but I'm un-sure myself if the blend door is going bad again or maybe it possibly being in the switch itself maybe a short or lack of voltage at times. Just speculation on my part.

Tony

 

Thanks for the reply. I knew that this subject has been beat to death on the forum, but all the posts I read never duplicated mine exactly. I'm glad to know i'm not the only one having this same problem. I may just cut the fan off and switch till what ever is messing up gives up. Then it won't be a search for a ghost problem. I may stop by the dodge place and have a talk with the service manager. I've known him for quiet a few years and he always shoots strait with me. If I find anything out I'll let you know.

 

Good deal, I'm assuming you have a newer truck than mine so probably being in the 3/36 warranty would not be a problem if you needed the blend door/actuator replaced under warranty unless your over mileage wise.

I tried several times with turning the fan blower off and switching the selector **** to different modes-defrost,floor vent,in-between settings,etc with no luck of it selecting what I put it on, the air still would only come out the front vents. Only after the truck set for two to three hours and I decided to go somewhere was when I started up the truck fan was off position and I heard the thump sound and so far it's been working like it should. Tomorrow may be a different story so yes talk to the service manager and see what he has to say.

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Tony

 

I believe there's a TSB out for the blend door. I don't remember the number of the TSB I will try to get the number and post it.