have a 03 f150 with atc the ac blows out the defrost the rest of the atc seems to work ok

 

You have a vacuum hose leak to the system. Check the hose that goes to the fender side of the battery, its the most common area to break.

 

Hi Randy, did you ever find a vacuum leak on your '03? Just wondering if that was the problem or if it was something else. I've got the same issue with my '03 F150 too.

 

I had the same problem with the A/C blowing the defrost only. I searched high and low, all vaccuum tuvbes looked good. I brought it into the dealer for repair. They said the problem was the ATC assembly and I needed part #2L3019980AA automatic temperature control for $540!! Plus $200 in labor for a total of $740!! I said no %#@&%$% way!! I have fashioned a 1/8" steel bar with a handle that I push through the driver side vent to push the vent door open to allow air flow through the front panel. Anybody have any other suggestions?

 

Ok, checked the elecronic unit, no codes ('03 s'crew lariat), can feel teensy bit of vacuum at the hose which goes to the vacuum motor which pulls the air from defrost to vent. how much vacuum should there be at the diverter motor? can't find a leak where the hose goes through the firewall (after spreading F150 dash all over the garage floor. Do the vacuum motors fail? How much vacuum makes it out of the electronic control unit? Has any one here heard of this problem getting resolved? I know what the Ford dealer will say...no thanks!