SM Split CS Series Heat Pump
SM Split CS Series Heat Pump8733825873 (2020/05)
28 | Troubleshooting
Subject to change without prior notice
TROUBLESHOOTING
A possible fault may be one or a combination of causes and solutions. Check each cause and adopt
“process of elimination” and or verification of each before making any conclusion.
Unit Troubleshooting
Problem Possible Cause Checks and Corrections
ENTIRE UNIT DOES
NOT RUN
Power Supply Off Close disconnect, apply power
Blown Fuse/Tripped Breaker
Replace fuse or rest circuit breaker. If using fuses, ensure
they are the correct size.
Voltage Supply Low
If voltage is below minimum voltage specified on unit data
plate, contact local power company.
Thermostat
Set the fan to “ON,” the fan should run. Set thermostat to
“COOL” with the lowest temperature setting, the unit
should run in the cooling mode (reversing valve
energized). Set unit to “HEAT” with the highest
temperature setting, the unit should run in the heating
mode. If neither the blower or compressor run in all three
cases, the thermostat could
be miswired or faulty. To ensure miswired or faulty
thermostat verify that 24 volts is available on the
condensing section low-voltage terminal strip between
“R” and “C,” “Y” and “C,” and “O” and “C.” If the blower
does not operate, verify that there is 24 volts between
terminals “G” and “C” in the air handler. Replace the
thermostat if defective.
UNIT OFF DUE TO
HIGH-PRESSURE
CONTROL
Discharge Pressure is Too
High
If in “COOLING” mode: Lack of or inadequate water flow.
Entering water temperature is too warm. Scaled or
plugged condenser.
If in “HEATING” mode: Lack of or inadequate load side
fluid flow. Blower inoperative, clogged filter
or restrictions in duct work.
Refrigerant Charge
The unit is overcharged with refrigerant. Reclaim
refrigerant, evacuate and recharge with the factory
recommended charge.
High-Pressure Switch
Check for a defective or improperly calibrated high-
pressure switch.
UNIT OFF TO
LOW-PRESSURE
CONTROL
Suction Pressure
Too Low
If in “COOLING” mode: Lack of or inadequate airflow.
Entering air temperature is too cold. Blower inoperative,
clogged filter or restrictions in duct work.
If in “HEATING” mode: Lack of or inadequate water flow.
Entering water temperature is too cold. Scaled or plugged
condenser.
Refrigerant Charge
The unit is low on refrigerant. Check for refrigerant leak,
repair, evacuate and recharge with factory recommended
charge.
Low-Pressure Switch
Check for defective or improperly calibrated low-pressure
switch.
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