Technical Description; Troubleshooting - resideo Honeywell Home DR90 Guide D'installation Professionnelle

Technical Description

DR90 uses a refrigeration system similar to an air
conditioner to remove heat and moisture from incoming
air and add heat to the air that is discharged. Hot, high-
pressure refrigerant gas is routed from the compressor
to the condenser coil. The refrigerant is cooled and
condensed by giving up its heat to the air that is about
to be discharged from the unit. The refrigerant liquid
then passes through a filter drier and capillary tubing
which causes the refrigerant pressure and temperature
to drop. It next enters the evaporator coil where it
absorbs heat from the incoming air and evaporates.
The evaporator operates in a flooded condition,
which means that all the evaporator tubes contain
liquid refrigerant during normal operation. A flooded
evaporator should maintain nearly constant pressure
and temperature across the entire coil, from inlet to
outlet.

Troubleshooting

CAUTION: Servicing the DR90 with its high pressure refrigerant system and high voltage
circuitry presents a health hazard which could result in death, serious bodily injury, and/or
property damage. Service should only be performed by a qualified service technician.
Problem
No dehumidification. Neither
fan nor compressor run and the
ventilation timer is OFF.
No dehumidification. Compressor
does not run but fan runs when
there is a call for dehumidification
and the ventilation control is OFF.
Fan runs when there is a call
for dehumidification and the
ventilation control is OFF, but the
compressor cycles on and off too
frequently.
DR90 Dehumidification System 69-2407EFS—02
STRAINER/FILTER
Recommended Troubleshooting Steps
1. Unit unplugged or no power to outlet.
2. Humidity control set too high or defective.
3. Loose connection in internal or control wiring.
4. Defective Compressor relay.
5. Defective control transformer.
6. Optional Condensate Pump Safety Switch open.
1. Defective compressor run capacitor.
2. Bad connection in compressor circuit.
3. Defective compressor overload.
4. Defective compressor.
5. Defrost thermostat open.
6. Optional Condensate Pump Safety Switch open.
1. Low ambient temperature and/or humidity causing unit to cycle
through defrost mode.
2. Defective compressor overload.
3. Defective compressor.
4. Defrost thermostat defective.
5. Dirty air filter(s) or airflow restricted.
6. Low refrigerant charge, causing defrost control to cycle.
7. Bad connection in compressor circuit.
DRIER
CONDENSER
EVAPORATOR
COMPRESSOR
CAPILLARY
TUBES
ACCUMULATOR
M27404
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