I just installed a new evaporator coil in a walk in cooler. Everything seems to be working fine temp wise, but there is frost on the suction line to the compressor and compressor is cool at that spot. The system is r22 45psi low and 160 high. I suspect I need to adjust the txv for more super heat but didn't want to try as a first option. Anybody have any other ideas. any questions let me know, thanks