I have a 2006 screw with the 5.4 and I get a hissing type noise from the A/C. It cycles every 7 seconds and sounds like it's coming from the far passenger vent area. It sounds like it's recharging itself or something. I've taken it into the dealer and the first time they said it was the vacuum driven system then the second time they said it was the freon recharging itself. Is every 7 seconds a little to often? It seems to get louder the longer I drive. Needless to say after a four hour trip to the beach hearing this hissing every 7 seconds drives me crazy. It will hiss then stop for seven seconds then hiss again. Anyone??? Thanks.

 

Take it back again. Both of those answers are full of crap.

Investigate your state's lemon laws and bring a copy along with you...

Steve

 

Really, considering Freon hasn't been used in over a decade, it was canned in '94.

The hissing is likely a vacuum leak. Check underhood hoses for any obvious signs of cracking or damage.

 

I was thinking of taking it to a shop that just does A/C work and have them tell me what's wrong then take that back to Ford and have them fix it under warranty and raise hell with the dealership for not fixing it in the first place. I love the truck but Ford needs some better techs. This isn't the first issue that has taken multiple trips to fix. The last one was a vibration noise under the hood that took three trips back before someone fixed it. This might be my last Ford, that Toyota Crew Max keeps looking better.

 

The freon Ford uses is R-134A ( the differance between the old and new is that the old had chlorine molocules, the new does not). Ford uses an expansion valve where others use a metering device to regulate the amount of freon passing through the evaporator coil.The expansion valve allows pressure to build to a certain point and then release's it into the coil, thus the hissing and the time period between. When the metering device is used and sometimes it will be an orfice type the freon passes through at a set and study rate.

 

Just FYI "Freon" was a trademark name of DuPont's R-12 refrigerant, though it kinda worked into the lexicon. Due to hippies b*tching in the early 90's the use was banned in 1994, reason being chlorofluorocarbons are so incredibly stable(chlorine and fluorine the two most electro-negative elements) are the they make it to the ozone layer without reacting(decomposing). Also why CFC's were used as propellants for shakey cans, the gas wouldn't react with whatever was in the can, paint, lube, whatever.

R-134a is the standard now since it's by chemical nature not a ClFC.

 

I have the same issue in my '06 SCrew. Hissing/gurgling from the passenger dash/floorboard area. It has done this since the day I bought it.....very annoying. The A/C has never been quite as cold as I would like it to be but it would still get the cabin cooled off if given enough time. But this spring/summer it has actually gotten worse, and it's only a year old! I turned it on the other day and at stop lights it actually blew warm air.

I am going to take it to the dealership when I get a chance, but I'll probably call them first just to see what they say over the phone. If anyone else has this problem and has a possible solution please post it. I'll post any news if/when I hear some.

*EDIT* airborne89, I just saw that you live in Huntersville. I live in Charlotte now, but last year I lived up the street from Huntersville Ford. That's the dealership I was planning on taking my truck to. Is that who you spoke with?

 

My '07 s'crew does the same thing. Very annoying. It's about every 10 seconds or so. It seems like when it makes the noise, the air coming out from the vents gets a little colder...just barely, and then it warms ever so slightly in between "hisses."

I also notice that sometimes the air temp from the vents, on both recirc and regular AC, will warm up significantly for a few seconds when I'm at about 1/2 throttle. Almost like the compressor cut-out is coming on early or something.

It doesn't give me a "warm and fuzzy" feeling about the system, and I'm a big guy....AC is very important to me, LOL!