Bosch LV012 - Page 36

36 | Troubleshooting LV Heat Pump Series
LV Heat Pump Series8 733 944 336 (2016/09) Subject to change without prior notice
No compressor operation
but fan runs
X
Is fault LED Blinking 4
times?
Condensate fault - poor
drainage
Check condensate pan for high water
level. Check drain line for blockages,
double trapping or inadequate
trapping.
Condensate fault -
blocked return air
Check condensate pan for high water
level. Check air filter and return air
duct work for blockage. Check that
there is adequate space between the
return air opening and walls or other
obstructions on free return
applications.
X
X
Is fault LED Blinking 5
times?
Brown out fault - low
supply voltage
Check primary voltage - ensure it is
within the limits listed on the unit
data plate.
Brown out fault -
overloaded control circuit
Check control voltage - if it is below
18 V check accessories connected to
the unit and ensure that they do not
exceed the VA draw shown on page
11.
Brown out fault - bad
thermostat connection
Check that thermostat wiring is
proper gauge and length, that it is
not damaged and that all
connections at the thermostat and
heat pump are secure.
X
Is fault LED Blinking 6
times?
Freeze fault, air coil - no
or low air flow
Check fan motor for proper
operation.
Check air filter
Inspect air coil for dirt/debris
Check duct work - are dampers
closed or blocked?
Freeze fault, air coil -
blocked return air
Check that there is adequate space
between the return air opening and
walls or other obstructions on free
return applications.
Freeze fault, air coil - low
refrigerant
Check refrigerant pressure with
gauge set.
X
X
No fault LED -
contactor not
energized
Thermostat not calling for
compressor operation
Ensure that the thermostat is on and
calling for "Y"
Bad thermostat
connection
Check "Y" connection from
thermostat. ensure that there is 24
VAC between "Y" and "C".
Loose wire to contactor
coil
Check wiring - ensure that there is 24
VAC across the contactor coil.
Burned out contactor coil
Test contactor with 24VAC (between
"R" and "C"). Ohm contactor coil - an
open circuit indicates a burned coil.
UNIT TROUBLESHOOTING
Problem Mode Check Possible Cause Action