Bosch Greensource CDi Series Installation, Operation And Maintenance Manual page 35

SM Series Heat Pump
Problem Mode
Cooling
X
X
No compressor
operation but fan runs
X
X
Revised 07-17
UNIT TROUBLESHOOTING
Check
Heating
Is fault LED Blinking 4
times?
Is fault LED Blinking 5
times?
Is fault LED Blinking 6
times?
No fault LED - contactor
X not energized
Possible Cause
Condensate fault - poor Check condensate pan for high water level.
drainage Check drain line for blockages, double trapping
Check condensate pan for high water level.
Condensate fault -
blocked return air
there is adequate space between the return air
opening and walls or other obstructions on free
Brown out fault - low Check primary voltage - ensure it is within the
supply voltage
18 V check accessories connected to the unit and
Brown out fault - ensure that they do not exceed the VA draw
overloaded control circuit
Check that thermostat wiring is proper gauge and
Brown out fault - bad length, that it is not damaged and that all
thermostat connection connections at the thermostat and heat pump are
Check fan motor for proper operation.
Freeze fault, air coil - no
or low air flow
Check duct work - are dampers closed or
Freeze fault, air coil - Check that there is adequate space between the
blocked return air return air opening and walls or other obstructions
Freeze fault, air coil - low Check refrigerant pressure with gauge set.
refrigerant
Thermostat not calling for Ensure that the thermostat is on and calling for
compressor operation
Bad thermostat Check "Y" connection from thermostat. Ensure
connection that there is 24 VAC between "Y" and "C".
Loose wire to contactor Check wiring - ensure that there is 24 VAC across
coil
Burned out contactor coil
"R" and "C"). Ohm contactor coil - an open circuit
Troubleshooting | 35
Action
or inadequate trapping.
Check air filter and return air
duct work for blockage. Check that
return applications.
limits listed on the unit data plate.
Check control voltage - if it is below
shown on page # 11.
secure.
Check air filter
Inspect air coil for dirt/debris
blocked?
on free return applications.
"Y"
the contactor coil.
Test contactor with 24VAC (between
indicates a burned coil.
8733942411 (2017/06)