Bosch Greensource CDi Series Installation, Operation And Maintenance Manual page 37

SM Series Heat Pump
Problem Mode
Cooling
Unit not shifting into X
Cooling and Heating
Excessively cold supply
air temperature in
cooling or excessively
hot supply air X
temperature in heating
Excessively warm
supply air temperature
in cooling and/or X
excessively cool air in
heating
High humidity X
Revised 07-17
UNIT TROUBLESHOOTING
Check
Heating
Reversing valve solenoid
energized
X
Reversing valve solenoid
not energized
Reduced air flow
X
Air flow too high
X
High or low water
temperature
Air leakage
Loss of refrigeration
capacity
Air flow too high
Loss of refrigeration
capacity
Short cycling
Possible Cause
Check that the reversing valve solenoid is
Faulty solenoid
Check the resistance of the solenoid - an open
circuit may indicate a burned out solenoid.
Check that the reversing valve thermostat wire is
connected to the "O" terminal of the thermostat.
Miswired/faulty
thermostat
Check for a contact closure between "O" and "R".
Check that the wires from the thermostat to the
Loose wire on "O" unit are securely connected and that the wires
terminal from the electrical box to the reversing valve are
Dirty Filter
Consult blower performance table and increase
Fan speed too low
Consult blower performance table and increase
Excessive duct pressure
drop
Fan speed setting too Consult blower performance table and reduce fan
high
Inlet water temperature Check unit capacity vs. water temperature.
out of range
Leaky duct work
Low refrigerant Check refrigerant pressures with gauge set.
Fan speed setting too Consult blower performance table and reduce fan
high
Low refrigerant Check refrigerant pressures with gauge set.
Unit oversized Check unit performance against building load
Poor thermostat location Make sure that thermostat is not located by a
Troubleshooting | 37
Action
receiving 24 VAC. If so,
connected.
Replace filter.
fan speed if possible.
fan speed if possible.
speed if possible.
Inspect duct work.
speed if possible.
calculations.
supply air duct.
8733942411 (2017/06)