Hey everyone I could use a little help with a problem that is driving me crazy. The problem is with a walk in cooler. Its a 404a system. The evaporator freezes up on the upper half. It is freezing up overnight. I have replaced the TEV. I have not been able to check the proper super heat due to the customer goes in and out all day long. Shortly after the unit is running I begin to notice frost build up on 2 of the 3 lines coming out of the distributor going into the evaporator. The two that are frosting up go to the middle and top of the evaporator. The third line does not frost but just sweats. After running all night the suction line if froze up back to the compressor. The sight glass is full with refrigerant. My head pressure is 225 and suction is 45 with an ambient temp of 70. The walk is running at 42 with these pressures.

If anybody has any ideas that could help me I would greatly appreciate it.