Loss Of Charge Switch; Check Defrost Thermostat; Troubleshooting; Start-Up Checklist - Carrier Comfort 50VT-K Installation Instruction

13.4 seer2 single-packaged heat pump system with puron (r-410a) refrigerant single phase 2-5 nominal tons (sizes 24-60) three phase 3-5 nominal tons (sizes 36-60)
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50VT-K: Installation Instruction
Step 13 – System Information

Loss of Charge Switch

The loss of charge switch is a protective device wired into control circuit
(low voltage). It shuts off the compressor if abnormally low pressures
are present in the refrigeration circuit.
NOTE: Because these switches are attached to refrigeration system
under pressure, it is not advisable to remove this device for
troubleshooting unless you are reasonably certain that a problem exists.
If switch must be removed, remove and recover all system charge so that
pressure gauges read 0 psig. Never open system without breaking
vacuum with dry nitrogen.

Check Defrost Thermostat

The defrost thermostat is usually located on the lowest liquid leaving
circuit of the left condenser coil (see
32_F (0_C) and opens at 65_F (18_C).
The defrost thermostat signals heat pump that conditions are right for
defrost or that conditions have changed to terminate defrost. It is a
thermally actuated switch clamped to outdoor coil to sense its
temperature. Normal temperature range is closed at 32_  3_F (0 
1.7_C) and open at 65_  5_F (18  2.8_C).
NOTE: The defrost thermostat must be located on the liquid side of the
outdoor coil on the bottom circuit and as close to the coil as possible.
The factor location is on the left/back coil.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Fig.
25). The thermostat closes at
Fig. 25 – Defrost Thermostat

Troubleshooting

Refer to the Cooling and Heating Troubleshooting Chart
troubleshooting information.

Start-Up Checklist

Use the Start-Up Checklist.
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