I'm working on a beer cooler. That the compressor went out on. The system was set up for R12. When the new compressor was installed I had changed it over to RB276. I charged the unit so that my low side gauge was at 25 psi. This converts to ruffly 32 degrees F. This system does have a TXV. The gauge was not full at this point and the suction line is frosting back. I'm alittle lost at this point. I thought you should run the suction temp 5 to 10 degrees colder than box temp. Desired box temp 38 to 40 degrees. Any help would be great.