Carrier Weathermaster 48P030-100 Controls, Start-Up, Operation, Service, And Troubleshooting page 108

PROBLEM
Subcooling Mode Will Not Activate
Reheat Mode Will Not Activate
No Dehumidification Demand
3-Way Valve Malfunction
Unit Initiates a Humidi-mizer Reheat
Mode, but Supply Air Temperature is
Overheating/Overcooling the Space
Unit Initiates a Humidi-MiZer
Dehumidification Mode, but Supply Air
Temperature is Overheating/
Overcooling the Space
Table 87 — Humidi-MiZer Service Analysis
CAUSE
Circuit B compressors unavailable
General Cooling Mode problem
Humidi-MiZer relative humidity sensor not
functioning - RARH, SPRH, or field-installed RH
sensor
Humidi-MiZer temperature sensors not
functioning - SAT, CCT
No Dehumidification demand
3-way valve malfunction
Unit control software is not configured for
Humidi-MiZer system
Circuit B compressors unavailable
Humidi-MiZer relative humidity sensor not
functioning - RARH, SPRH, or field-installed RH
sensor
No Dehumidification demand
3-way valve malfunction
Unit control software is not configured for
Humidi-MiZer system
Relative Humidity setpoint is too low - discrete
input (Humidistat, Thermidistat, etc.)
Relative Humidity setpoint is too low - RH sensor
Software configuration error for the type of
relative humidity sensor being used
No humidity signal
No 24-v signal to input terminals
Solenoid coil burnout
Stuck valve
Humid-MiZer Vent Reheat Set Point is too low
Evaporator discharge temperature (CCT) or
Supply air temperature (SAT) thermistor is
reading incorrectly.
Valve controlling gas bypass around the
condenser is not functioning properly
Valve controlling refrigerant flow to the
condenser is not functioning properly
Modulating valves are not calibrated properly
Unit control software indicates a Humidi-MiZer
Reheat Mode, but the 3-way valve is not
functioning properly
Unit is not sized to meet load at the current
entering air and outdoor conditions.
Supply air setpoint for cooling is too high/low
Evaporator discharge temperature (CCT) or
supply air temperature (SAT) thermistor is
reading incorrectly.
Valve controlling gas bypass around the
condenser is not functioning
properly
Valve controlling refrigerant flow to the
condenser is not functioning properly
Modulating valves are not calibrated properly
Unit control software indicates a Humidi-MiZer
Reheat Mode, but the 3-way valve is not
functioning properly
Unit is not sized to meet the load at the current
entering air and outdoor
conditions.
Check alarm history for general cooling mode operation problems. See Table 86.
Check for Circuit B compressors locked out.
See Table 86.
Check that a relative humidity sensor is connected and that the appropriate sensor
is configured in the unit software, (Configuration
Check for 24 vdc from CEM (RARH, SPRH).
Check 4-20 ma signal from sensor.
See "Thermistor Troubleshooting," see page 106.
See "No Dehumidification Demand, below.
See "3-Way Valve Malfunction," below.
Check that the unit is configured for Humidi-MiZer
 
(Configuration DEHU D.SEL).
Check alarm history for general cooling mode operation problems. See Table 86.
Check for Circuit B compressors locked out.
Check that a relative humidity sensor is connected and that the appropriate sensor
is configured in the unit software, (Configuration
Check for 24 vdc from CEM (RARH, SPRH).
Check 4-20 mA signal from sensor.
See "No Dehumidification Demand," below.
See "3-Way Valve Malfunction," below.
Check that the unit is configured for Humidi-MiZer
 
(Configuration DEHU D.SEL).
Check/reduce setting on discrete humidity input device.
Check the dehumidification relative humidity trip point
 
(Configuration DEHU D.RH.S).
Check that the unit software is configured for the correct relative humidity sensor
 
(Configuration DEHU D.SEN). D.SEN = 1: RARH, 2:SPRH, 3: Discrete Input.
See page 94.
Check wiring and sensor.
Check using Service Test mode.
Check wiring.
Check transformer and circuit breakers.
Check RCB relay output.
Check continuous over-voltage is less than 10%.
Check continuous under-voltage is less than 15%.
Check for missing coil assembly parts.
Replace solenoid coil.
Replace valve. Replace filter drier.
Check the Vent Reheat Set Point Selection (Configuration
and Vent Reheat Setpoint (Configuration
Vent Reheat RAT Offset also (Configuration
Humid-MiZer controls set-up.
See "Thermistor Troubleshooting," page 106.
Check if SAT thermistor is in a location that is measuring stratified air.
See "Modulating Valves Not Functioning Properly."
See "Modulating Valves Not Functioning Properly."
Run valve calibration through Service Test.
See "3-Way Valve Malfunction."
Check product data tables or ECAT for rated capacity at current entering air and
outdoor conditions.
Check the unit supply air set point for cooling operation. This is the temperature
that the valves will modulate to meet during a dehumidification mode.
See "Thermistor Troubleshooting" on page 106.
Check if SAT thermistor is in a location that is measuring stratified air.
See "Modulating Valves Not Functioning Properly."
See "Modulating Valves Not Functioning Properly."
See "Modulating Valves Not Functioning Properly."
See "3-Way Valve Malfunction."
Check product data tables or ECAT for rated capacity at current entering air and
outdoor conditions.
108
REMEDY
 
DEHU D.SEN). See page 94.
 
DEHU D.SEN). See page 94.

 
DEHU D.V.CF)
 
DEHU D.V.HT). If used, check the
 
DEHU D.V.RA). See page 94 for