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FAULT
COOLING
X
X
X
No Compressor
Operation but Fan
Runs
X
X
X
X
No compressor or
fan
X
operation
Table 33 — Troubleshooting
HEATING
CHECK
High Pressure fault - no or low
water flow
High Pressure fault - high water
temperature
High Pressure fault - fouled or
Is fault LED Blinking
scaled water coil
1 time?
High Pressure fault - no or low
X
airflow
Low Pressure fault - no or low
airflow
Is fault LED Blinking
Low Pressure fault - low refrigerant Check refrigerant pressure with gauge set.
2 times?
Low Pressure fault - no or low
water flow
X
Low Pressure fault - low refrigerant
Freeze fault, water coil - no or low
water flow
Is fault LED Blinking
X
Freeze fault - low water
3 times?
temperature
Freeze fault - low refrigerant
Condensate fault - poor drainage
Is fault LED Blinking
4 times?
Condensate fault - blocked return
air
Brown out fault - low
supply voltage
Brown out fault -
Is fault LED Blinking
overloaded control
X
5 times?
circuit
Brown out fault - bad
thermostat connection
Freeze fault, air coil - no or low
airflow
Is fault LED Blinking
6 times?
Freeze fault, air coil - blocked
return air
Freeze fault, air coil - low
refrigerant
Thermostat not calling for
compressor operation
Bad thermostat connection
No fault LED -
X
contactor not
energized
Loose wire to contactor coil
Burned out contactor coil
Open compressor
overload
No fault LED -
Poor wiring connections
X
contactor energized
Burned out compressor
Bad thermostat
Power LED on
connection / faulty
thermostat
Low or no supply power
X
Power LED off
Faulty control transformer
POSSIBLE CAUSE
Check water valves and/or pumps for proper operation.
Check for water coil blockage.
Check water temperature - is it in range?
Check for proper flow rate and water temperature, but low
waterside temp rise in cooling.
Check fan motor for proper operation.
Check air filter.
Inspect air coil for dirt/debris.
Check ductwork - are dampers closed or blocked?
Check fan motor for proper operation.
Check air filter.
Inspect air coil for dirt/debris.
Check ductwork - are dampers closed or blocked?
Check water valves and/or pumps for proper operation.
Check for water coil blockage.
Check for proper flow rate and water temperature, but low
waterside temp drop in heating.
Check water valves and/or pumps for proper operation.
Check for water coil blockage.
Check water temperature - is it below 40°F entering? If heat
pump is connected to a closed loop with antifreeze check that
the "FREEZE 1" resistor on the UPM board has been cut to
set the unit to antifreeze mode.
Check refrigerant pressure with gauge set.
Check condensate pan for high water level. Check drain line
for blockages, double trapping or inadequate trapping.
Check condensate pan for high water level. Check air filter
and return air ductwork for blockage. Check that there is
adequate space between the return air opening and walls or
other obstructions on free return applications.
Check primary voltage - ensure it is within the limits listed on
the unit data plate.
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 35.
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.
Check fan motor for proper operation.
Check air filter.
Inspect air coil for dirt/debris.
Check ductwork - are dampers closed or blocked?
Check that there is adequate space between the return air
opening and walls or other obstructions on free return
applications.
Check refrigerant pressure with gauge set.
Ensure that the thermostat is on and calling for "Y".
Check "Y" connection from thermostat. Ensure that there is 24
VAC between "Y" and "C".
Check wiring - ensure that there is 24 VAC across the
contactor coil.
Test contactor with 24VAC (between "R" and "C"). Ohm
contactor coil - an open circuit indicates a burned coil.
Check for supply voltage at the load side of the contactor. For
3 phase models check phase rotation and voltage at all 3
phases.
Look for signs of heat on the wiring insulation. Check that all
wiring connections are secure and properly torqued.
Does compressor hum when power is applied? If not check
the resistance of the compressor windings using the values
shown in the compressor characteristics chart. Note that the
compressor must be cool (70°F) when checking the windings.
Check thermostat and wiring. Check unit terminal block for 24
VAC between "Y" and "C" and "G" and "C".
Ensure that the supply voltage to the unit is with in the range
shown on the unit data plate.
Check for 24 VAC between "R" and "C" on the unit terminal
block. For 75 and 100 VA transformers, check that the
transformer circuit breaker has not tripped. Check low voltage
circuit for overload conditions or short circuits before replacing
the transformer.
63
SOLUTION
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