Carrier Aquazone 50PTH024 Installation, Start-Up And Service Instructions Manual page 60

FAULT COOLING HEATING
No compressor or
X
fan operation
No fan operation
X
(PSC motor)
No fan operation
(constant torque X
motor)
No fan operation
(constant airflow X
motor)
Unit not shifting
X
into cooling
Excessively cold
supply air
temperature in
cooling or
X
excessively hot
supply air
temperature in
heating
Excessively warm
supply air
temperature in
X
cooling and/or
excessively cool
air in heating
High humidity X
Table 25 — Troubleshooting (cont)
CHECK POSSIBLE CAUSE
Power LED on Bad thermostat connection/
faulty thermostat
Low or no supply power
X
Power LED off
Faulty control transformer
Fan relay
Faulty motor
energized
X
No fan operation signal
Fan relay not
energized
Bad fan relay
No fan operation signal
Loose wiring
X
Faulty motor
No fan operation signal
Loose wiring
Interface board problems
X
Faulty motor
Reversing valve
solenoid Faulty solenoid
energized
Miswired/faulty thermostat
Reversing valve
solenoid not
energized
Loose wire on "O" terminal
Dirty Filter
Fan speed too low
X Reduced airflow
Excessive duct pressure
drop
Airflow too high Fan speed setting too high
High or low
Inlet water temperature out
water
of range
temperature
X
Air leakage Leaky ductwork
Loss of
refrigeration Low refrigerant
capacity
Airflow too high Fan speed setting too high
Loss of
refrigeration Low refrigerant
capacity
Unit oversized
Short cycling
Poor thermostat location
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.
Check supply voltage from the fan relay to the motor.
Check that all motor wires are secure. With power off
spin the motor shaft - noise, resistance or uneven motion
can be signs of motor failure.
Check for 24 VAC across the fan relay coil. Check all
wiring connections.
If the relay coil is energized but the relay does not pull in,
check the resistance across the relay coil - an open
circuit is an indicator of a faulty relay.
Check for 24 VAC between "G" and "C".
Check all wiring connections.
Check all wiring connections at motor and control box.
Check supply voltage to the motor. Check that all motor
wires are secure. With power off spin the motor shaft -
noise, resistance or uneven motion can be signs of
motor failure.
Check for 24 VAC between "G" and "C".
Check all wiring connections. Make sure that the
thermostat connection plug is securely connected.
Check all wiring connections at motor and control box.
Check that power and control harnesses are securely
connected.
Make sure that the interface board is not damaged and
that all DIP switches are in the proper configuration
(refer to the blower performance tables).
Check supply voltage to the motor. Check that all motor
wires are secure. Move the "TEST" DIP switch to "ON"
and the other switches to "OFF" on the "ADJUST" switch
block on the interface board - the motor should run at
70% torque when "G" is called.
With power off spin the motor shaft - noise, resistance or
uneven motion can be signs of motor failure.
Check that the reversing valve solenoid is receiving 24
VAC. If so, check the resistance of the solenoid - an
open circuit may indicate a burned out solenoid.
Check that the reversing valve thermostat wire is
connected to the "O" terminal of the thermostat. Check
for a contact closure between "O" and "R".
Check that the wires from the thermostat to the unit are
securely connected and that the wires from the electrical
box to the reversing valve are connected.
Replace filter.
Consult blower performance table and increase fan
speed if possible.
Consult blower performance table and increase fan
speed if possible.
Consult blower performance table and reduce fan speed
if possible.
Check unit capacity vs. water temperature.
Inspect ductwork.
Check refrigerant pressures with gauge set.
Consult blower performance table and reduce fan speed
if possible.
Check refrigerant pressures with gauge set.
Check unit performance against building load
calculations.
Make sure that thermostat is not located by a supply- air
duct.
60
SOLUTION