I'v'e noticed that ever since I got my 07 Screw that cold air form the AC does not start until you get the RPM's up a little just after getting going. Then you're good. Here lately my problem is just the opposite. I've got a miss fire somewhere so the truck is running rough until I find the origin of the problem, but I noticed now that about 80% of the time the AC is blowing slightly cool until I back off the gas and the RPM's drop... then the cold air comes. Back on the gas, RPM's back up and the cold turns back to "cool" again. I've checked the Freon by trying to add some and the gauge showed to be in the full area. Go figure. I'm stumped. Got any idea?

 

When you added freeon and checked did you use one of those quick bottles from the store that only looks at the low side. If so your missing the high side info. You could have a bad fan clutch or blocked condenser. have some one watch the pressure and ac clutch as you rev up the truck to about 1500 to 2000 with the ac on max. If the an clutch starts to cycle thats why your at cool and not cold. Then you can start to find what is causing it to cycle high pressure or low. Also does the temp out side matter if its cold or not.

 

Yep. I did use one of those quick freon cans from O'Reilly's. Don't think it matters if it's really hot outside or not so hot. Still does the same thing. After I've driven a few miles and I stop and sit and idle it will finally get real cold and it will stay that way. Gets warmer when I start pushing the engine getting moving again. I'm not an AC man so I'm pretty dumb to this low and high side stuff. But I'll have an AC man have a look with full test guages. Thanks for the input. I'll check the clutch for cycling.

 

One of the bad things about the cans from O'Reillys is that there isn't any oil in the 134A. I would recommend getting your AC serviced by evacuating the system then refilling it with the correct amount of oil and coolant. A good auto shop will have the AC test system. It shouldn't be that expensive either.

 

Those cans cause more damage then good.

Please read my thread on that. https://www.f150forum.com/f2/ac-blowing-very-very-cold-268717/

There are some good ac techs on this forum.
If I were you I would go get that fixed the right way before your compressor fails and destroys a lot of parts. Hopefully it won't.

 

Thanks guys for the info and advice. I appreciate it!

 

No problem. Hopefully it is something minor. Let us know what you end up doing. That way if someone else has a similar problem you can be their guide for fixing it.!

Best of luck to ya

 

Ok... found the problem that was causing the truck to misfire. It was a leaking thermostat housing. The housing is right next to the #5 coil. The water was leaking down inside around the coil and so water was in contact with the plug and coil connection. Changed both coil and plug and the truck runs good... all cylinders firing properly. Pulled the thermostat housing and re-sealed and put it back on and no leak. As far the AC?... STRANGEST THING... since the misfire is gone, the AC has no temp fluctuation anymore. It has not skipped a beat for cold air since I fixed the misfire. Maybe the sensors were fouling due to the misfire, I don't know. Just wanted to share the find and outcome.

 

Wonder if the truck shuts down the ac when a miss fire is detected

 

Interesting. I had a 94 SHO that did the same thing. I was too poor/lazy at the time to bother investigating it.