Attention: TDR Forum Junkies 
Howdy, I see a lot of AC issues but in searching for my symptoms, I didn't find a thread so I am looking for info.
My 2008 6.7 Megacab is only blowing hot air from the vents. The compressor is running all the time if the AC switch is turned on, never cycles the clutch off at all. I am hoping to spend some time with some gauges on it tonight to try and learn more but I was hoping someone had a similar issue they had dealt with. The truck was working fine until I picked it up from a shop that replaced the turbo....coincidence? Hopefully but in doing a quick check of lines and wiring that is in the proximity of the turbo, I don't find any issues. I picked up one of the quick fill 134 Freon cans and when it is attached and the truck is running, the gauge on the can sits on zero. The only time the needle will move is when I turn the truck off and then the needle shoots up to the max side of the green scale on the gauge. I don't think its freezing the evaporator since it doesn't work for any period of time....hot air blows from the startup of the truck. Checked the two fuses related to HVAC and they are fine, the temp sliders in the control unit are working.....or at least will cause it to blow hotter air when I slide em to the hot side.
Since the compressor clutch is on the whole time, its throwing me for a loop on trouble shooting, most issues are related to freezing the evap or compressor kicking out too much with a low charge.....I am stumped.
My 2008 6.7 Megacab is only blowing hot air from the vents. The compressor is running all the time if the AC switch is turned on, never cycles the clutch off at all. I am hoping to spend some time with some gauges on it tonight to try and learn more but I was hoping someone had a similar issue they had dealt with. The truck was working fine until I picked it up from a shop that replaced the turbo....coincidence? Hopefully but in doing a quick check of lines and wiring that is in the proximity of the turbo, I don't find any issues. I picked up one of the quick fill 134 Freon cans and when it is attached and the truck is running, the gauge on the can sits on zero. The only time the needle will move is when I turn the truck off and then the needle shoots up to the max side of the green scale on the gauge. I don't think its freezing the evaporator since it doesn't work for any period of time....hot air blows from the startup of the truck. Checked the two fuses related to HVAC and they are fine, the temp sliders in the control unit are working.....or at least will cause it to blow hotter air when I slide em to the hot side.
Since the compressor clutch is on the whole time, its throwing me for a loop on trouble shooting, most issues are related to freezing the evap or compressor kicking out too much with a low charge.....I am stumped.
