I have a 08' f-150 4.2L 5spd. and my a/c seems to be having problems when I first crank the truck on it blows hot air. Once I get going the a/c starts cooling and works fine but if I sit in idle the compressor turns on and off. checked the system its charged. Im stumped and dont know what it may be reason would be for compressor to turn off and on would be the system has no free-on but it does. Can anybody help!!!

 

Mine did this after I went mudding. I figured out that it was probably debris in the A/C Clutch that was causing the poor idling performance. Maybe that is something you should look into.

Also, its been made clear to me that these trucks with traditional Fan Clutches do not pull a lot of air when idling. If your Fan Clutch is bad, it will be even worse.

 

The compressor cycling on and off is normal, as far as I know. As long as it is not short cycling (on/off, on/off very quickly).

And it's well known that the A/C in these trucks sucks when not moving. Normal.