Carrier WeatherMaker 48TC Series Service And Maintenance Instructions page 14

PROBLEM
Subcooling Reheat Mode Will
Not Activate
Hot Gas Reheat Mode Will Not
Activate
No Dehumidification Demand
CRC Relay Operation
RLV, CLV or LDV Valve
Operation
RDV Valve Operation
(NOTE: Normally Closed
When De-energized)
Low Latent Capacity in
Subcooling or Hot Gas
Reheat Modes
Low Sensible Capacity in
Normal Cool or Subcooling
Reheat Modes
Low Suction Pressure and
High Superheat During
Normal Cool Mode
Low Suction Pressure and
High Discharge Pressure
RDV Valve Cycling On/Off
Circuit B Will Not Operate
With Circuit A Off
LEGEND
CRC — Cooling/Reheat Control
CLV — Cooling Liquid Valve
RLV — Reheat Liquid Valve
RH — Relative Humidity
RDV — Reheat Discharge Valve
Table 4 — Humidi-MiZer Troubleshooting
CAUSE
General cooling mode problem
No dehumidification demand
CRC relay operation
Circuit RLV, CLV or LDV valve problem
General cooling mode problem
No dehumidification demand
CRC relay operation
Circuit RLV, CLV or LDV valve problem
Circuit RDV valve is not open
Outdoor temperature too low
Relative humidity setpoint too low — Humidistat Check/reduce setting on accessory humidistat.
Relative humidity setpoint too low — RH sensor On units with DDC, verify the RH sensor is reading properly and
No humidity signal
No 24V signal to input terminals
No power to output terminals
Relay outputs do not change state
No 24V signal to input terminals
Solenoid coil burnout
Stuck valve
No 24V signal to input terminals
Solenoid coil burnout
Stuck valve
CLV valve open or leaking
RDV valve open or leaking
General cooling mode problem
RDV valve open or leaking
General cooling mode problem
Both RLV and CLV valves closed
Hot Gas Reheat mode low suction pressure
limit
Normal operation. Motormaster outdoor fan
control requires operation of circuit A.
See Cooling Service Troubleshooting (Table 5).
See No Dehumidification Demand, below.
See CRC Relay Operation, below.
See CLV, RLV or LDV Valve Operation, below.
See Cooling Service Troubleshooting (Table 5).
See No Dehumidification Demand, below.
See CRC Relay Operation, below.
See CLV, RLV or LDV Valve Operation, below.
See RDV Valve Operation, below.
Check the LTLO is functioning properly.
that the setpoint is set properly.
Check wiring. Check humidistat or humidity sensor.
Check the dedicated Humidi-MiZer transformer for voltage or
tripped circuit breaker.
Check wiring.
Check transformer and circuit breaker.
Check wiring.
Replace faulty relay.
Check CRC Relay Operation.
Check wiring.
Check transformer and circuit beaker or fuses.
Check continuous over-voltage is less than 10%.
Check under-voltage is less than 15%.
Check for missing coil assembly parts.
Check for damaged valve enclosing tube.
Replace valve. Replace filter drier.
Check RDV relay operation.
Check wiring.
Check transformer and circuit breaker or fuses.
Check continuous over-voltage is less than 10%.
Check under-voltage is less than 15%.
Check for missing coil assembly parts.
Check for damaged valve enclosing tube.
Replace valve. Replace filter drier.
See CLV Valve Operation, above.
See RDV Valve Operation, above.
See Cooling Service Troubleshooting (Table 5).
See RDV Valve Operation, above.
See Cooling Service Troubleshooting (Table 5).
See RLV and CLV Valve Operation, above.
Normal Operation During Mixed Circuit Subcooling and Hot Gas
Reheat Modes at Lower Outdoor Temperatures.
None
14
REMEDY