Carrier AQUAZONE 50HQP072-120 Installation And Service Instructions Manual page 32

FAULT HEATING COOLING
Only Compressor Runs
Unit Does Not Operate in
Cooling
Insufficient Capacity/
Not Cooling or Heating
Properly
High Head Pressure
Low Suction Pressure
Low Discharge Air
Temperature in Heating
High Humidity
LEGEND
FP — Freeze Protection
HP — High Pressure
LED — Light-Emitting Diode
LP — Low Pressure
RV — Reversing Valve
Table 18 — Troubleshooting (cont)
POSSIBLE CAUSE
X X Thermostat wiring
X X Fan motor relay
X X Fan motor
X Reversing valve
X Thermostat setup
X Thermostat wiring
X X Dirty filter
X Reduced or no airflow in
heating
X Reduced or no airflow in
cooling
X X Leaky ductwork
X X Low refrigerant charge
X X Restricted metering device
X Defective reversing valve
X X Thermostat improperly
located
X X Unit undersized
X X Scaling in water heat
exchanger
X X Inlet water too hot or cold
X Reduced or no airflow in
heating
X Reduced or no water flow in
cooling
X Inlet water too hot
X Air temperature out of range
in heating
X Scaling in water heat
exchanger
X X Unit overcharged
X X Non-condensables in
system
X X Restricted metering device
X Reduced water flow in
heating
X Water temperature out of
range
X Reduced airflow in cooling
X Air temperature out of range Too much cold vent air. Bring entering air temperature within design
X X Insufficient charge
X Too high airflow
X Poor performance
X Too high airflow
X Unit oversized
Check G wiring at heat pump. Jumper G and R for fan operation.
Check Y and W wiring at heat pump. Jumper Y and R for compressor
operation in Test mode.
Jumper G and R for fan operation. Check for line voltage across BR
contacts.
Check fan power enable relay operation (if present).
Check for line voltage at motor. Check capacitor.
Set for cooling demand and check 24-vac on RV coil and at control.
If RV is stuck, run high pressure up by reducing water flow and while
operating engage and disengage RV coil voltage to push valve.
Check for 'O' RV setup not 'B'.
Check O wiring at heat pump. Jumper O and R for RV coil.
Replace or clean.
Check for dirty air filter and clean or replace.
Check fan motor operation and airflow restrictions.
High external static. Check duct design and downstream interference.
Check for dirty air filter and clean or replace.
Check fan motor operation and airflow restrictions.
High external static. Check duct design and downstream interference.
Check supply and return-air temperatures at the unit and at distant
duct registers if significantly different, duct leaks are present.
Check superheat and subcooling.
Check superheat and subcooling. Replace.
Perform RV touch test.
Check location and for air drafts behind thermostat.
Recheck loads and sizing check sensible cooling load and heat pump
capacity.
Perform scaling check and clean if necessary.
Check load, loop sizing, loop backfill, ground moisture.
Check for dirty air filter and clean or replace.
Check fan motor operation and airflow restrictions.
High external static. Check duct design and downstream interference.
Check pump operation or valve operation/setting.
Check water flow adjust to proper flow rate.
Check load, loop sizing, loop backfill, ground moisture.
Bring return-air temperature within design parameters.
Perform scaling check and clean if necessary.
Check superheat and subcooling. Reweigh in charge.
Vacuum system and reweigh in charge.
Check superheat and subcooling. Replace.
Check pump operation or water valve operation/setting.
Plugged strainer or filter. Clean or replace.
Check water flow adjust to proper flow rate.
Bring water temperature within design parameters.
Check for dirty air filter and clean or replace.
Check fan motor operation and airflow restrictions.
High external static. Check duct design and downstream interference.
parameters.
Check for refrigerant leaks.
Check blower.
See 'Insufficient Capacity' above.
Check blower.
Recheck loads and sizing check sensible cooling load and heat pump
capacity.
32
SOLUTION