PHD4 Series K and WPH4 Series K: Installation Instruction
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
32
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
). The thermostat closes at
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.
C99029
Fig. 27 – Defrost Thermostat
Troubleshooting
Refer to the Cooling and Heating Troubleshooting Chart (
) for
troubleshooting information.
Start-Up Checklist
Use the Start-Up Checklist.
FEEDER TUBE
STUB TUBE
DEFROST
THERMOSTAT