Carrier 38AKS012 User's Manual | Page 10

Carrier Dryer User's Manual - 38AKS012.
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10

Compressor Overload — This overload interrupts
power to the compressor when either the current or internal
motor winding temperature becomes excessive, and automati-
cally resets when the internal temperature drops to a safe level.
This overload may require up to 60 minutes (or longer) to reset.
If the internal overload is suspected of being open, disconnect
the electrical power to the unit and check the circuit through the
overload with an ohmmeter or continuity tester.

Cycle-LOC™ Device (CLO) —  The Cycle-LOC de-
vice prevents the compressor from starting or running in a high
pressure, loss-of-charge or freezestat open situation. Reset the

Cycle-LOC device by setting the thermostat to eliminate cool-
ing demand and return it to the original set point. If the system
shuts down again for the same fault, determine the possible
cause before attempting to reset the Cycle-LOC device.

Low-Pressure/Loss-of-Charge Switch (LPS) —
When the liquid line pressure drops below 7 psig (48 kPa), the
LPS opens 24-v power to the compressor contactor and stops
the compressor. When the pressure reaches 22 psig (152 kPa),
the switch resets and the compressor is allowed to restart.

High-Pressure Switch (HPS) — When the refriger-
ant high-side pressure reaches 426 psig (2937 kPa), the HPS
opens 24-v power to the compressor contactor and stops the
compressor. When the pressure drops to 320 psig (2206 kPa),
the switch resets and the compressor is allowed to restart.

Refrigerant Service Ports — Each unit system has
3 service ports: one on the suction line, one on the liquid line,
and one on the compressor discharge line. Be sure caps on the
ports are tight.

High Flow Valves — Located on the compressor hot gas
and suction tubes are high flow valves. Large black plastic caps
distinguish these valves with O-rings located inside the caps.
These valves cannot be accessed for service in the field. Ensure
the plastic caps are in place and tight or the possibility of refrig-
erant leakage could occur.

Cooling — Set space thermostat to OFF position. Set
system selector switch at COOL position and fan switch at
AUTO. position. Adjust thermostat to a setting below room
temperature. Compressor starts on closure of contactor.

Check cooling effects at a setting below room temperature.

Check unit charge. Refer to Refrigerant Charge section on
page 9.

Reset thermostat at a position above room temperature.

Compressor will shut off.
TO SHUT OFF UNIT — Set  system  selector  switch  at  OFF
position. (Resetting thermostat at a position above room tem-
perature shuts unit off temporarily until space temperature ex-
ceeds thermostat setting.) Units are equipped with Cycle-
LOC™ protection device. Unit shuts down on any safety trip
and remains off. Check reason for safety trip.

Compressor restart is accomplished by manual reset of the

thermostat by turning the selector switch to OFF position and
then to ON position.

Sequence of Operation — At start-up, the thermostat
calls for cooling. With all safety devices satisfied, the compres-
sor contactor and fan contactor energize, causing the compres-
sor and outdoor (condenser) fan motor to operate. Contacts
close, allowing the field-supplied and -installed indoor (evapo-
rator) fan contactor to function. The recommended field-
supplied and -installed liquid line solenoid valve will also
open, allowing the system to function in cooling. As cooling
demand is satisfied, the thermostat contacts break, deenergiz-
ing the contactor causing the system to shut off. The liquid line
solenoid valve closes, minimizing the potential for refrigerant
migration at this time. The compressor does not restart until the
thermostat again calls for cooling. The system is protected by a
Cycle-LOC device so that the compressor will not start if a
high-pressure or low-pressure fault occurs. Compressor restart
is accomplished by manual reset of the thermostat by turning
the selector switch to OFF position and then to ON position.
This should be done only once. If system shuts down due to the
same fault, determine the problem before attempting to reset
the Cycle-LOC device.

Fig. 9A — Cooling Charging Chart — 38AK008,012

and 38AKS008,009,012 (60 Hz)

Fig. 9B — Cooling Charging Chart — 38AK008,012

and 38AKS008,009,012 (50 Hz)

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