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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 to
repeat the process.
5.3 Troubleshooting
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
(Sec. 3.3 & 5.7A)
3. Loose connection in internal or control wiring.
4. Defective Compressor relay.
5. Defective control transformer.
6. Low pressure Control open (Sec 3.7 & 5.10).
7. Optional Condensate Pump Safety Switch open
(Sec 5.11).
No dehumidification, compressor does not run but
fan runs with fan switch and ventilation timer OFF
and humidity control turned to ON.
1. Defective compressor run capacitor (Sec. 5.6).
2. Bad connection in compressor circuit (See
Fig. 4).
3. Defective compressor overload (Sec. 5.6A).
4. Defective compressor (Sec. 5.6).
5. Defrost thermostat open (Sec. 5.8).
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 (Sec. 5.6A).
3. Defective compressor (Sec. 5.6).
4. Defrost thermostat defective (Sec. 5.8).
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
position. 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 fan circuit (See Fig. 4).
2. Obstruction prevents fan impeller rotation.
3. Defective fan.
4. Defective fan relay.
5. Defective fan capacitor.
Fan runs with fan switch ON. Fan does not run
with ventilation timer activated.
1. Ventilation timer set to manual & switched OFF.
2. Time not correct on ventilation timer.
3. Defective ventilation timer.
4. Defective fan switch.
Evaporator coil frosted continuously, low
dehumidifying capacity.
1. Dirty air filter(s) or airflow restricted.
2. Excessively restrictive ducting connected to unit.
3. Defrost thermostat loose or defective (Sec. 5.8).
4. Low refrigerant charge
Unit not providing ventilation. Ventilation timer not
operating correctly.
1. If timer is not functioning correctly reset timer
and reprogram (Sec. 3.5).
2. Check control wire connections (check
connections at fresh air damper also).
3. Defective fresh air damper (Sec. 5.9).
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 (Sec. 5.8).
4. Air filter dirty (Sec. 4.1 & 4.2).
5. Defective defrost thermostat (Sec 5.8).
6. Low refrigerant charge (Sec. 5.4).
7. Air leak such as loose cover or ducting leaks.
8. Defective compressor (Sec. 5.6).
9. Restrictive ducting (Sec. 2.4).
10. Optional Condensate Pump Safety Switch open
(Sec 5.11).
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; only the fan should run.
Disconnect the wires.
3. Connect the yellow and blue pigtails from the
main unit together; the compressor and fan
should run.
4. If these tests work, the main unit is working
properly. You should check the control panel and
field control wiring for problems next.
5. Remove the control panel from the mounting box
and detach it from the field installed control
wiring. Connect the blue, yellow, and green wires
from the control panel directly to the
corresponding colored pigtails on the main unit.
Leave the violet, white and red wires
disconnected!