Therma-Stor Products Group UA-135H - Manual (Page 15)

15
FOR HVAC INSTALLER AND HOMEOWNER
6. Service
CAUTION:
Servicing the UA-135H 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. Only qualified service people should service
this unit.
6.1 Technical Description
The UA-135H 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 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.
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
6.2 Troubleshooting
No dehumidification, neither impeller 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 open.
No dehumidification, compressor does not run but impeller fan
runs with fan switch and ventilation timer OFF and humidity
control turned to ON.
1. Defective compressor run capacitor.
2. Bad connection in compressor circuit.
3. Defective compressor overload.
4. Defective compressor.
5. Defrost thermostat open.
Impeller fan runs with fan switch and ventilation timer OFF, but
compressor cycles on & off.
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. Impeller fan does not run
with fan switch in either position.
Impeller fan does not run with ventilation timer activated.
Compressor runs briefly but cycles on & off with humidity
control turned to ON.
1. Loose connection in impeller fan circuit.
2. Obstruction prevents impeller fan rotation.
3. Defective impeller fan.
4. Defective impeller fan relay.
5. Defective impeller fan capacitor.
Impeller fan runs with fan switch ON. Impeller fan does not run
with ventilation timer activated.
1. Defective ventilation timer.
2. Time not correct on ventilation timer.
3. Ventilation timer set to manual & switched OFF.
4. Defective fan switch.
Evaporator coil frosted continuously, low dehumidifying
capacity.
1. Defrost thermostat loose or defective.
2. Low refrigerant charge
3. Dirty air filter(s) or airflow restricted.
4. Excessively restrictive ducting connected to unit.
Unit not providing ventilation. Ventilation timer not operating
correctly.
1. If timer is not functioning correctly reset timer and reprogram.
2. Check control wire connections (check connections at fresh air
damper also).
3. Defective fresh air damper.
4. Defective fan switch.
Unit removes some water, but not as much as expected.
1. Air temperature and/or humidity have dropped.
2. Humidity meter and or thermometer used are out of calibration.
3. Unit has entered defrost cycle.
4. Air filter dirty.
5. Defective defrost thermostat.
6. Low refrigerant charge.
7. Air leak such as loose cover or ducting leaks.
8. Defective compressor.
9. Restrictive ducting.
10. Optional Condensate Pump Safety Switch open.
Unit Test to determine problem:
1. Detach field control wiring connections from main unit.
2. Connect the yellow and green pigtails from the main unit together;
Ultra-Aire 135H Installer’s & Owner’s Manual