Help!! A/C blows warm air...Dealer says it's OK
 

I have a 2004 F-150 4.6.

The A/C has started to blow warm air.

I have been to the dealer twice. The dealer says the compressor is good, R-134 is good... no leaks in system. One line hot and one line cold. It does blow some cool air at idle if its parked in the shade.. enough to get a 30 degree drop between A/C and out side air. Thus.. they say its OK.

Can anyone tell me if the Blend door on a 2004 F-150 is operated by Electric or Vacuum? Curious, I developed a vacuum leak at the same time that the A/C took a dump... engine is idleing rough.. don't know if its related? However, computer has not thrown any codes for a rough idle. Makes me think its A/C related.

Could it be that it has a vacuum leak on the blend door activator and it is sucking air past the heater core instead of the evaporator?

Could the Condensor be clogged and still get good readings on both the high and low sides?

Any ideas appreciated. Its driving me crazy and its miserable driving in a hot truck ... :help:

The "30º drop" is the best it should perform is BULL HOCKEY!
The Vent temps should reach about 40º inside a shop even at 100º outside.
The Sun does add tons of BTU's so 40º vents immeadiately outside just doesn't happen quickly.

You could have a leaky blend air door, Use wide welder clamp syle vice grips etc to clamp off the heater hoses.
Condenser air flow has to be strong, How good is the fan clutch?
Does adding a shop fan in front of the grille help?
Pressures in range?
Leaking fresh air door will warm up a cab running down the road, The AC can't cool 100º air in one pass, it cools recirculated air quite well to 40º.

Any trusty shops in the area that could look at it other than the dealer?

Take it to another dealer.


Better yet, take it to a highly reputable independent shop, or even one that specializes in A/C repair.

If you are somewhat local, I can suggest a number of places. If not, start looking around.