Boscat

I posted a while ago about my truck (07 f 250 5.4 litre) switching to the defrost for no reason but only when the intake seems to lose vacuum. Soon as I let of the pedal and regain vacuum at the intake it switches back to where ever I have it set. The new thing that is going on now is that the a/c never shuts off. It does not matter where I have the knob set the a/c is on. the only place it is off is when you put the dial in the middle when everything is turned off. I will be pulling camper soon that weighs in at 8500 with bikes and gear and need all the power I can get. I dont like running with the a/c on when the truck is almost maxed out already. Any one seen this before?

KStromberg

This might be associated with your Electronic Auto Temperature Control Module or EATC. You can do a self-test on it yourself to get DTCs and go from there.

Here is a good link on how to do the self test:

I have a 2007 ford f-250 king ranch 4x4.My blowe... - JustAnswer

Let us know what codes you come up with if any. I hope this is the problem and it solves your situation. Otherwise, I think there is also a relay under the dash???

__________________
-1992 Ford F-150 (winter truck)
-1998 Lincoln Mark VIII LSC (fun car)13.591@101.72mph

Boscat

I dont think that applies to my truck as I do not have that option. The fact that it goes to defrost when driving is definatly related the fact it looses vacuum cause as soon I let of the pedal it goes back to where i had it set. Now the reason the a/c stays on all the time could that also be related to the fact that it looses vacuum at the control?