Bosch GreenSource SM024 - Unit Troubleshooting; NO COMPRESSOR OPERATION BUT FAN RUNS; NO COMPRESSOR OR FAN OPERATION; NO FAN OPERATION-ECM CONSTANT AIRFLOW MOTOR

Greensource CDi Series SM
Greensource CDi Series SM Model8733819578 (2019/02)
46 | Unit Troubleshooting
Subject to change without prior notice
UNIT TROUBLESHOOTING
Unit Troubleshooting
Problem Check Possible Cause Action
NO COMPRESSOR
OPERATION BUT
FAN RUNS
No fault LED—
Contractor
Energized
Open compressor overload Check for supply voltage at the load
side of the contractor. For 3-phase
models, check phase rotation and
voltage at all three phases.
Poor wiring connections Look for signs of heat on the wiring
insulation. Check that all wiring
connections are secure and properly
torqued.
Burned out compressor Does compressor hum when power is
applied? If not check the resistance of
the compressor winding using the
values shown in the compressor
characteristics chart. Note that the
compressor must be cool (70ºF) when
checking the windings.
NO COMPRESSOR
OR FAN
OPERATION
Power LED
blinking steadily
Bad thermostat connection/
faulty thermostat
Check thermostat and wiring. Check
unit terminal block for 24 VAC
between “Y” and “C” and “G” and “C.”
Power LED OFF
Low or no supply power Ensure that the supply voltage to the
unit is within the range shown on the
unit data plate.
Check for continuity across fuse F4.
Faulty control transformer Check for 24 VAC between “R” and
“C” on the unit terminal clock. For 75
and 100 VA transformers, check that
the transformer circuit breaker has not
tripped. Check low voltage circuit for
overload conditions or short circuits
before replacing the transformer.
NO FAN
OPERATION—ECM
CONSTANT
AIRFLOW MOTOR
See Action
No fan operation signal
Check for 24 VAC between “G” can
“C.” Check all wiring connections.
Make sure that the thermostat
connection plug is securing
connected.
Loose wiring
Check all wiring connections at motor
and control box. Check that power
and control harnesses are securely
connected.
Faulty motor
Check supply voltage to the motor.
Check that all the motor wires are
secure. With the power off, spin the
motor shaft—noise, resistance, or
uneven motion can be signs of motor
failure.