Carrier 50RTG - Manual (Page 24)

24
Table 22 — Troubleshooting
LEGEND
RV — Reversing Valve
FAULT HEATING COOLING POSSIBLE CAUSE SOLUTION
Main Power Problems X X Green Status LED Off Check line voltage circuit breaker and disconnect.
Check for line voltage between L1 and L2 on the contactor.
Check for 24 VAC between R and C on controller.
Check primary/secondary voltage on transformer.
HP Fault — Code 2
High Pressure X Reduced or no water flow in
cooling Check pump operation or valve operation/setting.
Check water flow adjust to proper flow rate.
X Water temperature out of
range in cooling Bring water temperature within design parameters.
X Reduced or no airflow in
heating Check for dirty air filter and clean or replace.
Check fan motor operation and airflow restrictions.
Dirty air coil — construction dust etc.
External static too high. Check Tables 4-12.
X Air temperature out of range
in heating Bring return air temperature within design parameters.
X X Overcharged with refrigerant Check superheat/subcooling vs typical operating condition.
X X Bad HP switch Check switch continuity and operation. Replace.
LP/LOC Fault — Code 3
Low Pressure/Loss of
Charge X X Insufficient charge Check for refrigerant leaks.
X Compressor pump down at
start-up Check charge and start-up water flow.
FP1 Fault — Code 4
Water Freeze Protection X Reduced or no water flow in
heating Check pump operation or water valve operation/setting.
Plugged strainer or filter. Clean or replace.
Check water flow adjust to proper flow rate.
X Inadequate antifreeze level Check antifreeze density with hydrometer.
X Improper freeze protect set-
ting (30
F vs 10 F)
Clip JW2 jumper for antifreeze (10 F) use.
X Water temperature out of
range Bring water temperature within design parameters.
X X Bad thermistor Check temperature and impedance correlation.
FP2 Fault — Code 5
Air Coil Freeze
Protection X Reduced or no airflow in
cooling Check for dirty air filter and clean or replace.
Check fan motor operation and airflow restrictions.
External static too high. Check Tables 4-12.
X Air temperature out of range Too much cold vent air. Bring entering air temperature within
design parameters.
X Improper freeze protect set-
ting (30
F vs 10 F)
Normal airside applications will require 30 °F only.
X X Bad thermistor Check temperature and impedance correlation.
Condensate Fault —
Code 6 X X Blocked drain Check for blockage and clean drain.
X X Improper trap Check trap dimensions and location ahead of vent.
X Poor drainage Check for piping slope away from unit.
Check slope of unit toward outlet.
Poor venting. Check vent location.
X Moisture on sensor Check for moisture shorting to air coil.
Over/Under Voltage —
Code 7
(Auto Resetting) X X Under voltage Check power supply and 24 VAC voltage before and during operation.
Check power supply wire size.
Check compressor starting.
Check 24 VAC and unit transformer tap for correct power supply voltage.
X X Over voltage Check power supply voltage and 24 VAC before and during operation.
Check 24 VAC and unit transformer tap for correct power supply voltage.
Performance Monitor —
Code 8 X Heating mode FP2>125 F Check for poor airflow or overcharged unit.
X Cooling mode FP1>125 F
OR FP2< 40 F
Check for poor water flow or airflow.
FP1 and FP2
Thermistors — Code 9 X FP1 temperature is higher
than FP2 temperature Swap FP1 and FP2 thermistors.
X FP2 temperature is higher
than FP1 temperature Swap FP1 and FP2 thermistors.
No Fault Code Shown X X No compressor operation See scroll compressor rotation section.
X X Compressor overload Check and replace if necessary.
X X Control board Reset power and check operation.
Unit Short Cycles X X Dirty air filter Check and clean air filter.
X X Unit in 'Test Mode' Reset power or wait 20 minutes for auto exit.
X X Unit selection Unit may be oversized for space. Check sizing for actual load of space.
X X Compressor overload Check and replace if necessary.
Only Fan Runs X X Thermostat position Ensure thermostat set for heating or cooling operation.
X X Unit locked out Check for lockout codes. Reset power.
X X Compressor overload Check compressor overload. Replace if necessary.
X X Thermostat wiring Check Y and W wiring at heat pump. Jumper Y and R for compressor
operation in Test mode.