Service - Ultra-Aire XT105H Installation & Operation Instructions

Troubleshooting
CAUTION!
TROUBLESHOOTING SHOULD BE PERFORMED BY A QUALIFIED HVAC TECHNICIAN.
Symptom
Neither fan nor
compressor
running.
Dehumidification
is being called for.
Compressor is
not running.
Dehumidification
is being called for.
Fan is running.
Compressor
cycles on and off.
Dehumidification is
being called for.
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SERVICE

Possible Reason
1. Dehumidifier 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.
6. Open circuit between
FLOAT terminals.
1. Defective compressor
run capacitor.
2. Loose connection in
compressor circuit.
3. Defective compressor
overload.
4. Defective compressor.
5. Defrost thermostat open.
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 air
flow restricted.
6. Defective fan or relay.
Troubleshooting Procedure
WARNING!
ELECTRICAL SHOCK HAZARD:
ELECTRICAL POWER MUST BE PRESENT
TO PERFORM SOME TESTS. THESE TESTS
SHOULD BE PERFORMED BY A QUALIFIED
SERVICE PERSON.
Troubleshooting Procedure for Control
Related Issues
This method of diagnosis will test the 3 main
components of the control circuit individually to
indicate any potential problems. This is to be used
when the control will not activate the main unit.
1. Detach field control wiring connections from
the pigtails on the main unit.
2. Jumper a wire from the 24V terminal to the
FAN terminal; only the fan should run.
Disconnect when complete.
3. Jumper the 24V terminal to the DEHU
terminal; the fan and compressor should run.
Disconnect when complete.
4. If this test works, the main unit is working
correctly from a control standpoint.
5. Reconnect field control wiring to the Terminal
block on the main unit.
6. Remove the control panel cover and detach
the field wiring from the control connections.
7. Connect the 24V terminal and the FAN
terminal wires together; the fan only should
run. Disconnect when complete.
8. Jumper a wire from the 24V and DEHU
terminal; fan and compressor should run.
Disconnect when complete.
9. If this test works, then the field control wiring
is ok.
10. If the problem persists, then the control is
most likely faulty.
Ultra Aire XT105H / XT155H / XT205H Installation Instructions
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