i know this is a similar problem to others that have been posted but my trucks not an 05. i have an 07 xl with 4.6 and 7500 miles. my a/c works fine in low 90's and below but as soon as its gets hotter then it just cant keep up so i switch it to max ac and will blow nice and cold for 10 minutes and then hardly at all for 5 minutes or so and get that humid ac off smell. also, no matter what ac setting its in and regardless of the outside temp, the hvac set up under the glove box makes an intermitting hissing sound and is quiet for a while and then hisses again. it has done all of these things since brand new but its finally hot enough to **** me off. i took it to the dealer and oddly enough they wont have time to look at it for a while. sounds like a low or high charge, any boby know for sure. thanks alot. hot as

 

I would find another dealer, if possible. Ford has been known to undercharge their A/C system on more than on occasion. My 04 F250 was this way as well as my 01 Expy.

 

Sounds like low freon. It probably is kicking off on a low pressure switch. Have someone throw some gauges on it. It will tell all.

 

yep, low charge. i finally got it into the dealer and they recharged it and now it works like a charm. i have to say though how much i love taking my cars to the dealer. it only took them 4.5 hours to recharge my ac with an appointment, they scratched my truck while washing it, and they forgot to call me when it was done. love it!!!!!!!!