Carrier 48HC D17 Series Service And Maintenance Instructions page 17

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 2 – 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 is
too low — Humidistat
Relative humidity setpoint is
too low — RH sensor.
Software configuration error
for accessory humidistat.
Software configuration error
for accessory humidity sensor.
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 con-
trol requires operation of circuit A.
See Cooling Service Analysis (Table 3).
See No Dehumidification Demand, below.
See CRC Relay Operation, below.
See CLV, RLV or LDV Valve Operation, below.
See Cooling Service Analysis (Table 3).
See No Dehumidification Demand, below.
See CRC Relay Operation, below.
See CLV, RLV or LDV Valve Operation, below.
See RDV Valve Operation, below.
Check Reheat2 Circuit Limit Temperatures
(ConfigurationHMZRRA.LO and RB.LO)
using ComfortLink Scrolling Marquee.
Check/reduce setting on accessory humidistat.
Check Space RH Setpoints (SetpointsRH.SP and RH.UN) and
occupancy using ComfortLink Scrolling Marquee.
Check Space Humidity Switch (Configuration
UNITRH.SW) using ComfortLink Scrolling Marquee.
Check RH Sensor on OAQ Input (Configuration
UNITRH.S) using ComfortLink Scrolling Marquee.
Check wiring. Check humidistat or humidity sensor.
Check using CoolReheat1 Valve Test (Service TestHMZRCRC)
using ComfortLink Scrolling Marquee.
Check MBB relay output.
Check wiring.
Check transformer and circuit breaker.
Check wiring.
Replace faulty relay.
Check using CoolReheat1 Valve Test (Service TestHMZRCRC)
using ComfortLink Scrolling Marquee.
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 using CoolReheat1 Valve Test (Service TestHMZRRHV.A or
RHV.B) using ComfortLink Scrolling Marquee.
Check MBB relay output.
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 Analysis (Table 3).
See RDV Valve Operation, above.
See Cooling Service Analysis (Table 3).
See RLV and CLV Valve Operation, above.
Normal Operation During Mixed Circuit Subcooling and Hot Gas Reheat
Modes at Lower Outdoor Temperatures.
None
17
REMEDY