I'm working on a freezer that had it's compressor changed by someone and now is using R-134a. My task was to change a bad condenser motor. The customer is using this unit as a medium temp beverage cooler. The thermostat was also replaced by others. After the unit was running for about 10 min., the operating pressures and temps are as folllows: 135hi/17low psig, 75deg. ambient, 44deg. box temp., 5deg. subcooling, and 56deg. superheat.
Here are the questions: Can a customer use a low temp unit for a med. to high temp. application without damage? It seems that the thermostat would satisfy before the superheat would come down. Based on the conditions given, is this unit undercharged or is there a restriction in the cap tube or is this normal for a low temp unit after being not in use for a duration? What would be the correct subcooling and superheat? Thank-you in advance for your responses.