Ok guys, I'm new to the forum, and have read a few things and really like what y'all have going here. I have a 2003 Model F150 4x4 that has always ran good for me, and has only had minor issues ever since I've had it. Not too bad considering it has 266,xxx miles on it and running 100 miles a day on the original motor & transmission.
Here's my problem - my air conditioning will only blow thru the defrost. I can hit vent on the control panel and it will blow thru the vents, but if i hit max ac it switches to defrost. I live close to Memphis, and it has gotten super hot around here and i really need this to work correctly. I'm hoping a little advice from y'all could help, bc a shop will cost me an arm and a leg. I'm not very knowledgeable about this stuff (have worked more on older vehicles) so i guess i'll need a fairly detailed reply if possible. I have looked under the hood looking for messed up vacuum lines but haven't seen any that looked bad.
Have your AC tested for PSI. It may need a additional charge of refrig espacially if you have never had it serviced. My 2003 needed about a half can a couple years ago. Check your codes for EATC failure related vacuum door problems. O-ring failure can bring about failure of the doors. check the Vacuum system for leaks. Low vacuum will affect operation of the doors. If you find a vacuum leak, fix it. You can get a can of refrig with a gauge on it. Fill your low pressure side to specs making sure about the temperature of outside air/PSI ratio. You can purchase a rebuilt air temp cantrol unit but replacing it, you may need some help. Internally the o-rings may be damaged leaking across. Getting the Refrig back up to PSI may help you for sometime and finding a Vacuum leak will save you lots of $$$$'s
location of the air has nothing to do with freon. There are 3-4 little vacuum cylinders that stroke doors inside the duct and route the air to the defrost, vents, floor, or combo. If you loose vacuum to the system, then the default is to go to defrost. You need to check the heater also. Can you put air to the floor, and vents, or always defrost. If if just screws up on "max ac" , then you probalby have a leak on that hose or cylinder for the "cab recirc door". The loss of vacuum causes the other doors to go to defrost.