2006 Mack CV713 A/C Cuts Out Erratically

[KevenH]

Hello all, I have a 2006 Mack CV713 Granite. Initially the A/C didn't work. A compressor was put on it before I got to it but the TXV and drier were not replaced. I replaced the TXV and drier, vacuumed, added oil and charged it up pressures are 20 on the low and 175-185 on the high side at 80 degrees ambient. It was working good and cycling properly for a few weeks. Now it kind of does what it wants sometimes theres no voltage to the compressor or the freeze switch wont kick out the compressor. I took the panel off the evap, the evaporator and the compressor suction line were iced up. I moved the freeze switch probe a little and it hasnt done that since. Binary switch is fine, freeze switch tests fine. With a power probe I test at the freeze switch and when it acts up there's no power supplied to it nor the 15 amp fuse next to the HVAC controls When the compressor is running I jave voltage there. When the a/c is cold and the freeze switch kicks out the compressor I have voltage on one side none on the other which is normal operation. When it does kick out the compressor some of the time the compressor won't reengage unless you shut the truck off and wait a little while. So whatever module controls the AC system seems to be doing erratic things. A wiring diagram would be helpful to trace the power path for the A/C compressor. Im also thinking maybe a fan issue as the fan rarely comes on when the a/c is running stationary, fan only comes on when coolant temp gets up to 190-200.