Table 32 — Troubleshooting (cont)

FAULT

HEATING

COOLING

POSSIBLE CAUSE

SOLUTION

Only Compressor Runs

X

X

Thermostat wiring

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 oper-

 

 

 

 

ation in test mode.

 

X

X

Fan motor relay

Jumper G and R for fan operation. Check for line voltage across BR

 

 

 

 

contacts.

 

 

 

 

Check fan power enable relay operation (if present).

 

X

X

Fan motor

Check for line voltage at motor. Check capacitor.

Unit Does Not Operate in

 

X

Reversing valve

Set for cooling demand and check 24 VAC on RV coil and at control.

Cooling

 

 

 

 

 

 

 

If RV is stuck, run high pressure up by reducing water flow and while

 

 

 

 

 

 

 

 

operating engage and disengage RV coil voltage to push valve.

 

 

X

Thermostat setup

Check for 'O' RV setup not 'B'.

 

 

X

Thermostat wiring

Check O wiring at heat pump. Check RV to ensure the valve is changing

 

 

 

 

over from heating and cooling modes. A 'click' should be heard when the

 

 

 

 

RV changes modes.

Insufficient Capacity/

X

X

Dirty filter

Replace or clean.

Not Cooling or Heating

 

 

 

 

X

 

Reduced or no airflow in

Check for dirty air filter and clean or replace.

Properly

 

 

 

heating

 

 

 

Check fan motor operation and airflow restrictions.

 

 

 

 

 

 

 

 

 

 

 

External static too high. Check blower Tables 8-10.

 

 

X

Reduced or no airflow in

Check for dirty air filter and clean or replace.

 

 

 

cooling

Check fan motor operation and airflow restrictions.

 

 

 

 

 

 

 

 

External static too high. Check blower Tables 8-10.

 

X

X

Leaky ductwork

Check supply and return-air temperatures at the unit and at distant duct

 

 

 

 

registers if significantly different, duct leaks are present.

 

X

X

Low refrigerant charge

Check superheat and subcooling Tables 15-25.

 

X

X

Restricted metering device

Check superheat and subcooling Tables 15-25. Replace.

 

 

X

Defective reversing valve

Manually check the four-way valve to ensure all valves are operational.

 

X

X

Thermostat improperly

Check location and for air drafts behind thermostat.

 

 

 

located

 

 

X

X

Unit undersized

Recheck loads and sizing check sensible cooling load and heat pump

 

 

 

 

capacity.

 

X

X

Scaling in water heat

Check for scale (water deposits) and clean if necessary.

 

 

 

exchanger

 

 

X

X

Inlet water too hot or cold

Check load, loop sizing, loop backfill, ground moisture.

High Head Pressure

X

 

Reduced or no airflow in

Check for dirty air filter and clean or replace.

 

 

 

heating

Check fan motor operation and airflow restrictions.

 

 

 

 

 

 

 

 

External static too high. Check blower Tables 8-10.

 

 

X

Reduced or no water flow in

Check pump operation or valve operation/setting.

 

 

 

cooling

Check water flow adjust to proper flow rate. See Table 14.

 

 

 

 

 

 

X

Inlet water too hot

Check load, loop sizing, loop backfill, ground moisture.

 

X

 

Air temperature out of range

Bring return-air temperature within design parameters.

 

 

 

in heating

 

 

 

X

Scaling in water heat

Check for scale (water deposits) and clean if necessary.

 

 

 

exchanger

 

 

X

X

Unit overcharged

Check superheat and subcooling. Reweigh in charge.

 

X

X

Non-condensables in

Evacuate the refrigerant, recharge the system, and then weigh the new

 

 

 

system

refrigerant charge.

 

X

X

Restricted metering device

Check superheat and subcooling per Tables 15-25. Replace.

Low Suction Pressure

X

 

Reduced water flow in

Check pump operation or water valve operation/setting.

 

 

 

heating

 

 

 

 

Plugged strainer or filter. Clean or replace.

 

 

 

 

 

 

 

 

Check water flow adjust to proper flow rate.

 

X

 

Water temperature out of

Bring water temperature within design parameters.

 

 

 

range

 

 

 

X

Reduced airflow in cooling

Check for dirty air filter and clean or replace.

 

 

 

 

Check fan motor operation and airflow restrictions.

 

 

 

 

External static too high. Check blower Tables 8-10.

 

 

X

Air temperature out of range

Too much cold vent air. Bring entering air temperature within design

 

 

 

 

parameters.

 

X

X

Insufficient charge

Check for refrigerant leaks.

Low Discharge Air

X

 

Too high airflow

Check blower Tables 8-10.

Temperature in Heating

X

 

Poor performance

See 'Insufficient Capacity'.

High Humidity

 

X

Too high airflow

Check blower Tables 8-10.

 

 

X

Unit oversized

Recheck loads and sizing check sensible cooling load and heat pump

 

 

 

 

capacity.

LEGEND

 

 

 

 

RV — Reversing Valve

 

 

 

 

42

Page 42
Image 42
Carrier 50PCH specifications Reduced or no water flow, Reduced airflow in cooling

50PCH specifications

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