Bosch GreenSource SM024 - EXCESSIVELY COLD SUPPLY AIR TEMPERATURE IN COOLING OR EXCESSIVELY HOT SUPPLY AIR TEMPERATURE IN HEATING

Unit Troubleshooting | 47Greensource CDi Series SM Model
8733819578 (2019/02)Greensource CDi Series SM Model
Subject to change without prior notice
FAN OPERATES
BUT THE MOTOR
DOES NOT
CHANGE SPEED—
ECM CONSTANT
AIRFLOW MOTOR
Is the motor
behavior only
observed during
startup?
Ramp-up programming
delays are still in effect
Wait at least 5 minutes after the start-
up and then change the fan operation
based on thermostat call.
Is the motor not
stopping when
there is no call
for cooling or
heating from
thermostat?
Thermostat is in continuous
fan mode
Change the thermostat setting to ON/
OFF (auto) fan operation instead of
continuous fan operation.
High-external
static
Dirty air filter, closed
dampers, grills, dirty air coil
Remove the air filter and check that all
of the dampers, register, and grills are
open and free flowing. If removing the
filter corrects the problem, clean or
replace it with a less restrictive filter.
Also check and clean as needed the
blower wheel and secondary heat
exchanger (if applicable).
UNIT NOT SHIFTING
INTO COOLING
AND HEATING
Reversing valve
solenoid
energized
Faulty solenoid
Check that the reversing valve
solenoid is receiving 12 VAC.
Check the resistance of the solenoid—
an open circuit may indicate a burned
out solenoid.
Reversing valve
solenoid NOT
energized
Miswired/faulty thermostat
Check that the reversing valve
thermostat wire is connected to the
“O” terminal of the thermostat.
Check for a contact closure between
“O” and “R.”
Loose wire on “O” terminal
Check that the wires from the
thermostat to the unit are securely
connected and that the wires from the
electrical box to the reversing valve
are connected.
EXCESSIVELY
COLD SUPPLY AIR
TEMPERATURE IN
COOLING OR
EXCESSIVELY HOT
SUPPLY AIR
TEMPERATURE IN
HEATING
Reduced air flow
Dirty Filter Replace filter.
Fan speed too low
Consult blower performance table and
increase fan speed if possible.
Excessive duct pressure
drop
Consult blower performance table and
increase fan speed if possible.
Unit Troubleshooting
Problem Check Possible Cause Action