Carrier 48TC series, Service And Maintenance Instructions, Page: 14 / 112

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