TrueDry DR90 Dehumidification System 69-2407—01
11
Technical Description
TrueDRY 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.
Problem
Recommended Troubleshooting steps
No dehumidification. Neither
fan nor compressor run and the
ventilation timer is OFF.
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.
No dehumidification. Compressor
does not run but fan runs when
there is a call for dehumidification
and the ventilation control is OFF.
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.
Fan runs when there is a call
for dehumidification and the
ventilation control is OFF, but the
compressor cycles on and off too
frequently.
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..
CONDENSER
EVAPORATOR
CAPILLARY
TUBES
ACCUMULATOR
COMPRESSOR
STRAINER/FILTER
DRIER
M27404
Troubleshooting
CAuTIOn:
Servicing the TrueDRY 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.
