Bosch BP070 Installation And Maintenance Manual page 27

Troubleshooting
Insufficient Unit undersized
cooling or
heating
Loss of conditioned
air by leakage
Airflow
Refrigerant charge
Compressor
Reversing Valve
Operating
pressures
TxV
Moisture,
noncondensables
UPM board
Compressor will
not run, no fault
trouble
blink code
shooting
Revised 01-11
Recalculate heating and or cooling loads. If excessive, possibly
adding insulation and shading will rectify the problem
Check for leaks in duct work or introduction of ambient air
through doors or windows
Lack of adequate air flow or improper distribution of air.
Replace dirty filter
Low on refrigerant charge causing inefficient operation
Check for defective compressor. If discharge is too low and
suction pressure is too high, compressor is not pumping
properly. Replace compressor.
Defective reversing valve creating bypass of refrigerant from
discharge of suction side of compressor. Replace reversing
valve
Compare unit operation pressures to the pressure/temperature
chart for the unit.
Check TxV for possible restriction or defect. Replace if
necessary.
The refrigerant system may be contaminated with moisture
or noncondensables. Reclaim refrigerant, replace filter dryer,
evacuate the refrigerant system, and recharge with factory
recommended charge.
Is Green
Power LED
light on and
no Red
Blink Code?
Subject to change without prior notice
Yes
Is there
power to
Yes
the "Y" Call
(C-Y)?
No
- Check all
No
power supplies
- Check all
safety switches
CP/BP Series 27
UPM Board
Yes
is Good
Is there 24 V
power from
C to CC?
Check for Red
No
Blink Code.
If Red Blink
Code is not
Check
present, replace
thermostat
UPM Board
settings and
configurations
for heat
pumps, and
wiring
6 720 220 045