09 STA, DATC blows cold all the time

[SMSgt09]

I have an 09 STA 4.6 with DATC when I first start it the truck the AC comes on and seems to be fine. Then after a few minutes say 2 to 5 minutes the fan speed increases and a min or two later it increases again.

Now that is only part of the problem. If I set the DATC to 60 degrees it blows out freezing cold air. If I set the DATC on any temp between 60 and 85 it blows out freezing cold air. The next step warmer is 90 and at that point it will change the vents to floor and blow out hot air. If I adjust it own one press of the button to 85 it blows out freezing cold air again.

I changed the driver’s side blend door actuator (BDA) out of desperation and nothing changed. When I changed out the driers side BDA I noticed that the blend door was not completely closed when I took out the old BDA and when I put the new BDA I had to turn the BDA to the left, counter clockwise to get it into the blend door then turn it to the right to make the screw holes match up. Which opened the blend door.

When I had the BDA out I took it apart and found things normal, no missing gears or any visible problems, which is what I expected because I could see it turning on the back side when I operate the controls. I took the gear out that opens the blend door, inserted it into the side of the blend door and the blend door moved freely. So the blend doors operate as they should, I presume.

This brings me back to the original problem I don’t get warm air at any setting other than 90 degrees F. The fan speed has a mind of its own however I cn adjust it with the fan speed control on the DATC.

Any ideas or suggestions? Do I need to change out the controls? Would that make a difference?

Thanks
Kent

 

[06bluez]

just a guess, but could possibly be an issue with the temp sensor which is behind the small vent just in front of the keys?

 

[SMSgt09]

I've had that out a couple of times, for other things, dash lights and such. I cleaned some dust off of it and looked at it but wasn't sure what I was even looking at.
Do you know the actual name of it so I can look to buy another one?
I'm considering buying an new controller but that is the last result. I did the two computer checks on the controller and no codes came up. I have also put my scan tool on the truck several times and it has some codes that I need to work out but nothing related to the DATC.
Thanks for the reply.
Kent
I found a cabin air temperature sensor for about $10.00. I"ll give it a try.
Does anyone know how the air is drawn through the cabin air temp sensor? Is there some kind of little vacuum fan that pulls the air through this?

 

[boominXplorer]

On the other side of the heater blend door is the switch for the heater control valve. If that little arm is broken you will not get heat. It's to the left of the glove box down on side of console. It's an arm that swings and hits the vacuum switch for the valve.

 

[SMSgt09]

On the other side of the heater blend door is the switch for the heater control valve. If that little arm is broken you will not get heat. It's to the left of the glove box down on side of console. It's an arm that swings and hits the vacuum switch for the valve.

I'll give it a look. Thanks

 

[SMSgt09]

I just thought I'd update on the progress of my DATC blowing cold all the time.

I took 06bluez suggestion, and the suggestion of a local friend. I replaced the cabin air temp sensor about $15.00. And replaced the ambient air temp sensor about $30.00.

I saved about $30.00 dollars by buying them on line from Village Ford. The parts are Motorcraft, they came quickly and did the job so I will use Village Ford again. When I go into the local dealer they always have to order the parts anyway so I figured I could order them, save some money and wait.

I have always suspected there was a ground problem because of erratic behavior with systems throughout the truck so I took off the 4 major grounding points under the hood, sanded the paint off the contact area and cleaned and replaced the ground wires.

I took it for a 35 mile test drive and the A/C worked perfectly.

I couldn't tell you which thing I did specifically that fixed the problem but it was all relatively cheap and easy to do.
I'll let you all know if anything changes.
Kent