Hi guys know im new but just one question got a problem with a 404a system. I keep getting high head pressure on the system ive checked the condenser, the suction and discharge valve plates of the compressor. Its a copland and it runs a blast freezer. Im starting to think that the tev could be a problem but it could also be air in the system, i also rodded out the shell and tube condensor but no luck, any answers? anybody.