Bosch EC Series - Page 44

Troubleshooting
No compressor
operation
Heating
Is the Fault LED
blinking two (2)
times on the
1
st
stage UPM
ONLY?
Is the Fault LED
blinkin
g four (4)
times on the 1
st
&
2
nd
stage UPMs?
If Yes, Circuit 1 is
affected.
If Yes, Circuit 2 is
affected.
Low-pressure fault—No or low
air flow.
• Check the water valves and/
or pumps for proper
operation.
• Check for water coil
blockage.
Low-pressure fault—Fouled or
scaled water coil.
Check for proper flow rate and
water temperature, and a rise in
water-side temperature in
cooling mode.
Low-pressure fault—Low
refrigerant.
Check refrigerant pressure with
a gauge set.
Heating
Is the Fault LED
blinkin
g five (5)
times on the
1
st
stage UPM
ONLY?
Is the Fault LED
blinkin
g nine (9)
times on the 1
st
&
2
nd
stage UPMs?
If Yes, Circuit 1 is
affecte
d.
If Yes, Circuit 2 is
affecte
d.
Freeze 1 fault, water coil—No
or low wa
ter flow.
• Check water valves and/or
pumps
for proper operation.
• Check for water coil
blocka
ge.
Freeze 1 fault, water coil—Low
water te
mperature.
• Check water temperature—Is
it belo
w 40°F entering?
• If heat pump is connected to
a close
d loop with
antifreeze, check that
position #5 (Freeze 1) of the
DIP switch SW1 on the UPM
board is in the ON position.
(
Refer to Fig. 13 and
Table 9
on page #28.)
(Refer
the Freeze Sensors
section
page #29.)
Freeze 1 fault, water coil—Low
refrige
rant.
Check refrigerant pressure with
a gauge set.
Cooling
Is the Fault LED
blinking six (6)
times on the 1
st
&
2
nd
stage UPMs?
Condensate fault—Poor
drainage.
• Check the condensate pan
for high water level.
• Check the drain line for
blockages, double trapping,
or inadequate trapping.
Condensate fault—Blocked
return air.
• Check the air filter and
return air duct work for
blockage.
• Check that there is adequate
space between the return air
opening and the walls or
other obstructions on free
return applications.
Compressor Troubleshooting
Problem Mode Check Then Possible Cause Action
44 |
EC Series Heat Pumps — 8733841499 (2024/05)