Just completed a warranty compressor change out on a York Sunline 3 ton RTU. After weighing in factory charge and running the unit in cooling to verify proper operation we found the head pressure fairly quickly (less than 2 mins) elevating to above 500 psi and trip out on high head. I was testing in a relatively low ambient (approx 40F). Coil is clear, OFM running in the right direction.
After consulting with the local York rep, he figures this is due to a lack of internal area in the condenser for a surplus of liquid refrigerant to stack up, as is possible with a traditional tube style condenser. He said he`s encountered this with the Micro Channel coils and low load/low ambient in the past.
Does this explanation sound legit? Anyone else encountered this?