Drove about 30 minutes to a wedding yesterday and A/C was working perfectly. Truck sat about 4 hours and was cool out when I started it to make the 30 minute drive back so I cranked the heat wide open until the cab warmed slightly. Once it warmed a little I turned the setting back towards the cooler setting but the air just kept getting hotter. The only way I could stop the air from blowing out hot like it was set on max heat was to set the control on max a/c, all other settings blow max heat! Can somebody help me with this problem or help me diagnose it. Thanks!

Oh, by the way, my truck is a 2006 F-350 XLT diesel CC 4x4 auto with the FX4 package

 

Thought it was in my sig, need to correct that.

 

Unless you had a control head malfunction, it sounds like the blend door actuator has failed and is stuck in the full hot position. It blows cold in the Max cool position because the water valve actuates with Max cool so no hot water flows through the heater core then.

 

What do I need to do to dignose this and fix this issue? can you help me?

 

The blend door actuator is mounted on top of the plenum. You can access it behind the glove box. Just observe the white colored shaft to see if it is turning when you move the control from hot to cold. You can also hear a difference in the sound of the airflow if it moves from hot to cold, a subtle difference but it is there. If the shaft doesnt move then the actuator is likely defective and needs replaced. It is held in with several screws that can be a chore to reach, but they can be reached. Shouldnt take more than an hour.

 

Shouldn't I check the conrol **** first or make sure that it is getting power? If so, is there an easy way to do that?

 

You can check the power at the fusebox, just refer to the owner manual for the correct fuse. I have however never had a bad control for one of these believe it or not and they have been using electronic blend doors for a long time. I have seen a few cracked ***** themselves on the F150.

 

About a month ago I pulled the face off the dash to run some wires. When I did that I disconnected all the swtches from the face, you know the light switch, the cigarette lighter, and theswitches for the heat and a/c. Hooked it all back up when I was fiinished and have had no problems. Just wanted to make sure that anything that I might have done at that timne wasn't the cause before I replaced the blend door actuator. That is one of the reasons I wanted to find out how I would check to see if all the controls and the wireing were funtioning properly first. Any thougts or suggestions?

 

I looked behind the glove box today and the only thing that I saw mounted on top was what looked to be a vacuum style motor with it's shaft running up and down in the very front of the heater box. When I turned the vent selector it moved up and down and the air outlet changed from defrost to front vent to floor vent. Is this the blend control unit or should I be looking for something else?

By the way, the first thing I checked when this all started was to see if any connections on the back of the control panel were loose. Everything looked good at the time.

 

That would be the mode door actuator. If you have manual AC the blend door actutor is square shaped offwhite or opaque box about 1/2 inch thick that sits flat on top of the plenum. You should have seen it very near the actuator, has an electrical connector visible from the glove box opening as well.

I just took a couple pics that may help of my 2004. I was thinking your 2006 was very close to the same. If you dont see this when you open the box let me know and Ill see if I can find a better reference.

 

I just checked the manual and it says yours is exactly the same setup

 

I did see that device when I was looking. Great pics! Do you have any idea what this part costs?

 

They vary but average 50-85 dollars. That one might come with the whole mounting bracket so it may be more. It usually isnt needed though. The actuator just clips onto that bracket and is easy to change out. Most controllers are screwed down on each corner.

 

Thanks, gonna look into it today.

 

Homer, just to let you know, picked up the part today, installed it as you stated and everything is working as it should again. Thanks so much for your help, installation went well and you saved me a TREMENDOUS amount of trouble since it probably would've been at the dealership a couple of days and cost me downtime at work. Thanks for your help, couldn't have done it with it!