1.Connect the low pressure side of the manifold gauge, the blue hose, to the low pressure port located on the suction side of the compressor, not the suction line as you would do with a standard air conditioning unit or a heat pump operating in the summer. Heat pumps will have an additional port just for this purpose located between the two refrigerant lines. Remember, heat pumps reverse the pump direction in the winter. The larger line, traditionally the suction line, will then be the high pressure line.
2.Attach the high pressure side of the manifold gauge, the red hose, to the port on the larger refrigerant line. This is the low pressure side during summer operation and the high pressure side during winter operation.
3.Connect the middle hose on the manifold gauge to the refrigerant tank and open the valve on the tank.
4.Set the refrigerant tank in a 5-gallon bucket partially filled with hot water.
5.Set the system thermostat to “Heat” and adjust the thermostat so that it runs. Now you can add freon the same way you would during the summer by opening the low-pressure valve on the manifold gauge.