The AC on my machine needs charged and I can't seem to get it to take any R134. I have the full gauge set and after I hook up the low side I can read the pressure on the system but when I try to add freon it won't transfer. I've recharged my trucks with no problem but can't figure out why the machine won't take the gas. After hooking up the gauges and opening the valves I've tried running the machine in all idle modes with the AC on high and also had a helper in the cab putting pressure on the pilot valves to run the engine at rated speed. Is there a check valve or a procedure I am missing?
Was the compressor turning? If so, it's possible that ambient temperature at the container and low side pressure were too close to allow this. post the ambient and low side pressure observed and maybe we can help you.
The compressor was cycling on and off. During the off cycle the pressure was about 25 and when the compressor kicked in it went to about 40. The ambient temp at the time was 85. I even tried sitting the can on top of the engine with the hopes of raising the pressure in the can to allow it to flow into the system. The can was at least 95-100 deg., all valves open, no restriction in the delivery lines and the needle valve was open. I followed the normal procedure as described on the can instructions shaking the can and held it both vertically and horizontally.
I know it sounds to simple but, have you checked the coolant flow to the heater? Had one this week where the owner was trying to fix the no cool situation. The heater valve was not shutting off the coolant.
try a different set of gauges. I had a coupler on the gauge set give me fits like you discribe
whats the high side pressure ? If the compressor isnt pumping, it wont take refrigerant