Bosch Greensource SM024 Installation, Operation And Maintenance Manual page 23

SM AH Series Heat Pump
Problem Possible Cause
INSUFFICIENT Unit undersized
COOLING OR
HEATING
Loss of
conditioned air by
leakage
Airflow
Refrigerant
charge
Compressor
Reversing Valve
Operating
pressures
TXV
Moisture,
noncondensables
BLOWER Thermostat
OPERATES
Wiring
BUT
COMPRESSOR
Safety Controls
DOES NOT
Compressor
overload open
Compressor
motor grounded
Compressor
windings open
Unit Troubleshooting
Checks and Correction
Recalculate heating and or cooling loads. If excessive, possibly adding
insulation and shading will rectify the problem
Check for leaks in duct work or introduction of ambient air through
doors or windows
Lack of adequate air flow or improper distribution of air. Replace dirty
filter
Low on refrigerant charge causing inefficient operation
Check for defective compressor. If discharge is too low and suction
pressure is too high, compressor is not pumping properly. Replace
compressor.
Defective reversing valve creating bypass of refrigerant from discharge
of suction side of compressor. Replace reversing valve
Compare unit operation pressures to the pressure/temperature chart
for the unit.
Check TXV for possible restriction or defect. Replace if necessary.
The refrigerant system may be contaminated with moisture or
noncondensables. Reclaim refrigerant, replace filter dryer, evacuate the
refrigerant system, and recharge with factory recommended charge.
Check setting, calibration, and wiring.
Check for loose or broken wires at compressor, capacitor, or contactor.
Check UPM board red default L.E.D. for Blink Code
If the compressor is cool and the overload will not reset, replace
compressor.
Internal winding grounded to the compressor shell. Replace
compressor. If compressor burnout, install suction filter dryer.
After compressor has cooled, check continuity of the compressor
windings. If the windings are open, replace the compressor.
Troubleshooting | 23
8733920846 (2014/01)