Have a 2001 F150 5.4L. It seems like over the years the A/C has slowly degraded to the point now that on hot days it feels like its barely putting out even somewhat cooler air. It's gotten to the point that my g/f refuses to ride in the truck on hot days.

I took it in to the dealer, they said the system is fully charged and claim that they measured the air output to be 40degrees.

Any suggestions on where to go from here? My memory from when I got the truck new was that it could get the interior very cool even on the hottest days... now when I get out of the truck on a warm day, my back is soaked with sweat even running the A/C on Max.

Suggestions?

 

Either the dealership is lying to you or you have the windows open! You should be able to "feel" 40 degree air blowing out of the vents, I'd make the dealer prove it to you right there in the shop. If the system is charged fully, then it could be a blend door problem. Honestly my best guess is that your system has developed a slow leak, and that it probably needs to be serviced. Properly diagnosed and then a complete evac and replace of the refrigeration. Do a quick search and you will find all sorts of answers.

 

I second that, took mine to the dealer only to be quoted 1000 for a failing clutch, leaky compressor and pulley too. Found out at a rad shop it was almost a pound low, recharged and snowing in July again. This is a year after the blendor went so beware. Then it was stuck on hot only so it was easily diagnosed.

 

double check that blend air door, Even a slight air leakage through the heater core will overcome the cool air.
Clamp off the heater hoses (vise grips or c-clamps) temporarily to see if the temp cools down.
Does the vent temps hit 40* inside the shop in the shade, but its warmer while moving?
The recirculaton door is open allowing hot outside air in. The AC can cool air about 30* each pass. When its sucking in 100* ouside air its going to cool it to 70* at best.