DH90 Dehumidifier • For HVAC Installer Only
CAUTION: Servicing the DH90 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.
No dehumidification, neither fan nor compressor
run with fan switch and ventilation timer 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. Low pressure control open.
7. Optional Condensate Pump Safety Switch
No dehumidification, compressor does not run
but fan runs when there is a call for dehumidi-
fication 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
Fan runs when there is a call for dehumidifica-
tion 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.
Fan does not run with fan switch in either