Справочник Пользователя для Carrier 50JS
exists, be sure that all supply- and return-air grilles are open and
free from obstructions, and that the air filter is clean. When
necessary, refer to Indoor Airflow and Airflow Adjustments
section to check the system airflow.
free from obstructions, and that the air filter is clean. When
necessary, refer to Indoor Airflow and Airflow Adjustments
section to check the system airflow.
METERING DEVICES — Refrigerant metering devices are fixed
orifices and are located in the inlet header to the indoor and
outdoor coils.
orifices and are located in the inlet header to the indoor and
outdoor coils.
LIQUID LINE STRAINERS — The liquid line strainers (to pro-
tect metering devices) are made of wire mesh and are located in the
liquid lines on the inlet side of the metering devices.
tect metering devices) are made of wire mesh and are located in the
liquid lines on the inlet side of the metering devices.
SYSTEM INFORMATION
TIME-DELAY RELAY — The Time-Delay Relay (TDR) is a
solid-state control, recycle delay timer which keeps indoor blower
operating for 60 sec. after thermostat is satisfied. This delay
enables blower to remove residual cooling in coil after compres-
sion shutdown, thereby improving efficiency of system. The
sequence of operation is that on closure of wall thermostat and at
end of a fixed on delay of 1 sec., fan relay is energized. When
thermostat is satisfied, an off delay is initiated. When fixed delay
of 60
solid-state control, recycle delay timer which keeps indoor blower
operating for 60 sec. after thermostat is satisfied. This delay
enables blower to remove residual cooling in coil after compres-
sion shutdown, thereby improving efficiency of system. The
sequence of operation is that on closure of wall thermostat and at
end of a fixed on delay of 1 sec., fan relay is energized. When
thermostat is satisfied, an off delay is initiated. When fixed delay
of 60
±
5 sec. is completed, fan relay is de-energized and fan motor
stops. If wall thermostat closes during this delay, TDR is reset and
fan relay remains energized. TDR is a 24-v device that operates
fan relay remains energized. TDR is a 24-v device that operates
within a range of 15v to 30v and draws about 0.5 amps. If the
blower runs continuously instead of cycling off when the fan
switch is set on AUTO, the TDR is probably defective and must be
replaced.
blower runs continuously instead of cycling off when the fan
switch is set on AUTO, the TDR is probably defective and must be
replaced.
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.
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 gages read 0 psi. Never open system
without breaking vacuum with dry nitrogen.
troubleshooting unless you are reasonably certain that a problem
exists. If switch must be removed, remove and recover all system
charge so that pressure gages read 0 psi. Never open system
without breaking vacuum with dry nitrogen.
CHECK DEFROST THERMOSTAT — There is a liquid header
with a brass distributor and feeder tube going into outdoor coil. At
the end of 1 of the feeder tubes, there is a 3/8-in. OD stub tube
approximately 3 in. long. (See Fig. 37.) The defrost thermostat
should be located on stub tube. Note that there is only 1 stub tube
used with liquid header, and on most units it is the bottom circuit.
with a brass distributor and feeder tube going into outdoor coil. At
the end of 1 of the feeder tubes, there is a 3/8-in. OD stub tube
approximately 3 in. long. (See Fig. 37.) The defrost thermostat
should be located on stub tube. Note that there is only 1 stub tube
used with liquid header, and on most units it is the bottom circuit.
DEFROST THERMOSTATS — 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 tempera-
ture range is closed at 30˚ +/- 3˚F and open at 80˚ +/- 5˚F.
changed to terminate defrost. It is a thermally actuated switch
clamped to outdoor coil to sense its temperature. Normal tempera-
ture range is closed at 30˚ +/- 3˚F and open at 80˚ +/- 5˚F.
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.
possible.
Fig. 36—Refrigerant Circuit
C99097
Fig. 37—Defrost Thermostat
C99029
FEEDER TUBE
STUB TUBE
DEFROST
THERMOSTAT
THERMOSTAT
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