[R4global]

Hello there:
I am working in a walking cooler, it is a Heatcraft unit, model CHMO40H2C I cannot find the serial number because the name plate tag is fade it out and the only information is left is the model number. Anyhow, beginning of problem, the high pressure will go up to 350psi then the condensing fan will come on, will cool down to 250psi then the condensing fan will go off, then pressure will build up again to the same pressure mention above fan comes on and so on and so forth. I thought might be a restriction on it, perhaps filter dryer, and also it builds up frost on the compressor and suction lines I thought might be overcharged or moister on the system. Took refrigerant out, pull it down to a good vacuum close to 30mg, change filter dryer, weight back refrigerant 22lbs according to manufacture. After everything is done problem came right back again. Is it the expansion valves? The only problem it has an electronic expansion valve and don’t know much about them at all. And is it OK to switch to the mechanical expansion valves? Please help!! :D