Bosch LV009 Installation And Maintenance Manual page 38

38 | Troubleshooting
Problem
No fan operation -
constant airflow motor
Unit not shifting into
cooling
Excessively cold supply
air temperature in
cooling or excessively
hot supply air
temperature in heating
Excessively warm supply
air temperature in
cooling and/or
excessively cool air in
heating
8 733 944 336 (2016/09)
UNIT TROUBLESHOOTING
Mode Check
X X
Reversing valve
solenoid energized
X
Reversing valve
solenoid not
energized
X X Reduced air flow
Air flow too high
High or low water
temperature
X X
Air leakage
Loss of refrigeration
capacity
Subject to change without prior notice
Possible Cause
Check for 24 VAC between "G" and
"C". Check all wiring connections.
No fan operation signal Make sure that the thermostat
Check all wiring connections at
motor and control box. Check that
Loose wiring
power and control harnesses are
Make sure that the interface board is
not damaged and that all DIP
Interface board problems
configuration (refer to the blower
Check supply voltage to the motor.
Check that all motor wires are
secure. Move the "TEST" DIP switch
to "ON" and the other switches to
"OFF" on the "ADJUST" switch block
Faulty motor on the interface board - the motor
should run at 70% torque whrn "G" is
called. With power off spin the
motor shaft - noise, resistance or
uneven motion can be signs of motor
Check that the reversing valve
solenoid is receiving 24 VAC. If so,
Faulty solenoid check the resistance of the solenoid -
an open circuit may indicate a
Check that the reversing valve
theromstat wire is connected to the
Miswired/faulty
"O" terminal of the thermostat.
thermostat
Check for a contact closure between
Check that the wires from the
thermostat to the unit are securely
Loose wire on "O"
connected and that the wires from
terminal
the electrical box to the reversing
Dirty Filter
Consult blower performance table
Fan speed too low
and increase fan speed if possible.
Excessive duct pressure Consult blower performance table
drop and increase fan speed if possible.
Fan speed setting too Consult blower performance table
high and reduce fan speed if possible.
Inlet water temperature Check unit capacity vs. water
out of range
Leaky duct work
Check refrigerant pressures with
Low refrigerant
LV Heat Pump Series
Action
connection plug is securely
connected.
securely connected.
switches are in the proper
performance tables).
failure.
burned out solenoid.
"O" and "R".
valve are connected.
Replace filter.
temperature.
Inspect duct work.
gauge set.
LV Heat Pump Series