Refrigerant Charging! When Confirming a Charge, Should You Always Have 18-21 Degree Temp Diff?

Refrigerant Charging! When Confirming a Charge, Should You Always Have 18-21 Degree Temp Diff? When you are confirming a refrigerant charge especially on a system with a fixed metering device, you may not get 18-21 degrees of the temperature difference between the return and supply even though the refrigerant charge is correct. This would be due to the high humidity in the building. The water condensing action of the evaporator coil takes too much of the heat exchange away from the air and therefore you only get maybe 14 or 15 degrees of temp difference. What you need to do is to check for the correct airflow and check for the correct charge and in the case of high humidity, finish the job then because as a service tech, you don't have another 1/2 an hour to an hour to wait to finally see that 18-21 degree temp diff. The Tech needs to have confidence in the Refrigerant Charging Method to get the job done in a Timely Manner!