59
Table 45 — Humidi-MiZer™ Service Analysis
LEGEND
PROBLEM CAUSE REMEDY
Subcooling Reheat Mode
Will Not Activate.
General cooling mode problem. See Cooling Service Analysis (Table 44).
No dehumidification demand. See No Dehumidification Demand, below.
Circuit RH1 valve is not open. See RH1 Valve Operation, below.
Hot Gas Reheat Mode
Will Not Activate.
General cooling mode problem. See Cooling Service Analysis (Table 44).
No dehumidification demand. See No Dehumidification Demand, below.
Circuit RH1 valve is not open. See RH1 Valve Operation, below.
Circuit RH2 valve is not open. See RH2 Valve Operation, below.
Outdoor temperature too low.
Check Reheat2 Circuit Limit Temperatures (Configuration→
HMZR→RA.LO and RB.LO) using ComfortLink™ Scrolling Marquee.
No Dehumidification Demand.
Relative humidity setpoint is too low —
Humidistat
Check/reduce setting on accessory humidistat.
Relative humidity setpoint is too low —
RH sensor.
Check Space RH Setpoint (Setpoints→RH.SP)
using ComfortLink Scrolling Marquee.
Software configuration error for accessory humi-
distat.
Check Space Humidity Switch (Configuration→UNIT→RH.SW) using
ComfortLink Scrolling Marquee.
Software configuration error for accessory
humidity sensor.
Check RH Sensor on OAQ Input (Configuration→UNIT→RH.S) using
ComfortLink Scrolling Marquee.
No humidity signal. Check wiring. Check humidistat or humidity sensor.
RH1 Valve Operation.
No 24V signal to input terminals.
Check using Cool→Reheat1 Valve Test (Service Test→HMZR→CRC)
using ComfortLink Scrolling Marquee.
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.
RH2 Valve Operation.
(NOTE: Normally Closed
When Deenergized)
No 24V signal to input terminals.
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.
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.
RH1 valve open or leaking. See RH1 Valve Operation, above.
Low Sensible Capacity
in Normal Cool or
Subcooling Reheat Modes.
RH2 valve open or leaking. See RH2 Valve Operation, above.
Low Suction Pressure and High
Superheat During Normal Cool Mode.
General cooling mode problem. See Cooling Service Analysis (Table 44).
RH2 valve open or leaking. See RH2 Valve Operation, above.
Low Suction Pressure General cooling mode problem. See Cooling Service Analysis (Table 44).
RH2 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 con-
trol requires operation of circuit A.
None
CV — Cooling Valve
RH — Relative Humidity
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