10. Service
CAUTION
CAUTION: Servicing the Ultra-Aire 65H 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. Please
contact your HVAC professional.
10.1 Technical Description
The Ultra-Aire 65H uses a refrigeration system similar to an
air conditioner’s 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 (See Figure 1). 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 strainer 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.
The mixture of gas and liquid refrigerant enter the
accumulator after leaving the evaporator coil. The
accumulator prevents any liquid refrigerant from reaching the
compressor. The compressor evacuates the cool refrigerant
gas from the accumulator and compresses it to a high
pressure and temperature
10.2 Troubleshooting
Neither fan nor compressor running. Dehumidification is
being called for. No fan call.
1. Unit unplugged or no power to outlet.
2. Humidity control set too high.
3. Loose connection in internal or control wiring.
4. Defective Compressor relay.
5. Defective control transformer.
Compressor is not running. Dehumidification is being
called for. No fan call.
1. Defective compressor run capacitor (Sec. 7.6).
2. Loose connection in compressor circuit.
3. Defective compressor overload (Sec. 7.6A).
4. Defective compressor (Sec. 7.6).
5. Defrost thermostat open.
Compressor cycles on and off. Dehumidification is being
called for. No fan call
1. Low ambient temperature and/or humidity causing unit
to cycle through defrost mode.
2. Defective compressor overload (Sec. 7.6A).
3. Defective compressor (Sec. 7.6).
4. Defrost thermostat defective (Sec. 7.8).
5. Dirty air filter(s) or air flow restricted.
Fan is not running. Dehumidification or fan is being
called for
1. Loose connection in fan circuit.
2. Obstruction prevents fan impeller rotation.
3. Defective fan.
4. Defective fan relay.
Low dehumidification capacity (evaporator is frosted
continuously). Dehumidification is being called for
1. Defrost thermostat loose or defective (Sec. 7.8).
2. Low refrigerant charge
3. Dirty air filter(s) or air flow restricted.
4. Excessively restrictive ducting connected to unit.
No ventilation. Ventilation is being called for.
1. Loose connection in ventilation control circuit
2. Loose connection in damper power circuit.
3. Defective fresh air damper.
FOR HVAC INSTALLER ONLY
Refrigeration System of Ultra-Aire 65H
12
Ultra-Aire 65H Installer’s & Owner’s Manual