Steps to Measuring Superheat
1. Attach your low side (suction) refrigerant gauge to the suction line service port at the condenser coil. You can identify the suction line because it is the larger of the two refrigerant lines.
2. Place a clamp on digital temperature probe near the suction line inlet to the condenser coil. Somewhere near the service port.
3. Read and record the pressure and corresponding temperature from your low side gauge. In this example, 130 PSIG for R-410A corresponds to 44F. 44F is the saturation temperature of the refrigerant in the evaporator coil.
4. Read and record the temperature from you digital temperature probe. In this example we will use 54F.
Subtract the temperature recorded from your gauges from the digital temperature reading. This example shows that the refrigerant entering the condenser is 10F warmer than the saturation temperature of the refrigerant. 54F (measured temperature) – 44F (saturation temperature) = 10F (superheat) The Compressor
3. Read and record the pressure and corresponding temperature from your low side gauge. In this example, 130 PSIG for R-410A corresponds to 44F. 44F is the saturation temperature of the refrigerant in the evaporator coil.
4. Read and record the temperature from you digital temperature probe. In this example we will use 54F.
Subtract the temperature recorded from your gauges from the digital temperature reading. This example shows that the refrigerant entering the condenser is 10F warmer than the saturation temperature of the refrigerant. 54F (measured temperature) – 44F (saturation temperature) = 10F (superheat) The Compressor
When the suction vapor is drawn from the suction line into the compressor, the cold refrigerant vapor absorbs heat from the compressor motor windings. If there is the proper amount of vapor present, the compressor will be cooled properly. If there is a lack of refrigerant vapor (such as an undercharged system), the compressor will run very hot.
After cooling the motor, the vapor is compressed to a high pressure/temperature gas and discharged into the hot gas line leading to the condenser coil. These hot gas temperatures average about 126F.
by Ron Walker