Bosch EP015 Installation And Maintenance Manual page 37

Troublehsooting
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 12-13
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.
Yes
Is Green
Power LED
light on and
no Red
Blink Code?
No
Subject to change without prior notice
Is there 24 V
Yes
power from
C to CC?
Is there
power to
the "Y" Call
(C-Y)?
Check
thermostat
settings and
No
configurations
for heat
pumps, and
wiring
- Check all
power supplies
- Check all
safety switches
37
EP Series
UPM Board
Yes
is Good
Check for Red
No
Blink Code.
If Red Blink
Code is not
present, replace
UPM Board
8733922168