SERVICE
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When servicing unit, turn off all electric power to unit to avoid shock hazard or injury from rotating parts.
Do not vent refrigerant to atmosphere when servicing
unit. Recover refrigerant during system repair or unit removal.
Diagnostic Codes
To access the LED indicator light, remove the front cover of the unit by removing the 3 screws holding it in place.
If the LED indicator light continuously flashes on for one second, then off for one second, the control is functioning
properly and no fault is present. A fast flashing LED indi- cates that a fault has been detected. Table 10 lists the num-
ber of quick flashes and the associated fault. If the system does not operate and the LED indicator does not flash, either the power is offto the control board or the control board has failed.
System Tests
formed continuously by the microprocesson If a fault is indicated, then the system allows only limited operation an- til the problem is resolved. If the problem resolves itself, then the code is cleared and operation resttmes.
THERMISTOR TESTS
not touch each other, and cable runs may be extended up to 200 feet.
With unit running, the thermistor integrity may be checked by measuring the dc voltage across the two thermistor con- nections. Approximate temperature is indicated in Table 11.
COMPRESSOR FAILURE
lf the System is in Cooling or Dehumidification
lf the System is in Heat Pump Heating Mode (38BK only)
After 5 minutes of opemtinn, if the tempemture indicated by the outdoor coil thermistor is not 4 ° F less than at the time
the call for heating started, then a compressor failure is indicated.
REVERSING VALVE FAILURE (38BK Only)
If the System is in Cooling or Dehumidification
ter 5 minutes of operation, if the temperature at the indoor coil is 4 ° F more than at the time the call for cooling started, then a reversing valve failure is indicated.
If the System is in Heat Pump Heating Mode
utes of operation, if the temperature indicated by the out- door coil is 4 ° F more than at the time the call for heating started, then a reversing valve failure is indicated.
Table 10 --System Fault Codes
NO. OF QUICK | SYSTEM FAULT |
LED FLASHES | |
2 | Room Air Thermistor |
3 | Indoor Coil Thermistor |
4 | Outdoor Coil Thermistor* |
5 | Compressor Malfunction |
6 | Reversing Valve Malfunction* |
7 | Outdoor Air Thermistor* |
8 | Indoor Fan Failure |
9 | Discharge Air Thermistor |
LEGEND |
|
LED
*Heat pump systems only,
NOTE: If the LED light continuously flashes on for one second, then
off for one second, the control is functioning propedy and no fault is present.
System Safeties and Interlocks
INDOOR FAN FAILURE
the indoor fan rpm is greater than 1700 rpm for 30 seconds, then this test indicates an indoor fan failure.
COMPRESSOR
is a time delay of 3 minutes between compressor turning off and turning back on.
INDOOR COIL FREEZE PROTECTION (Cooling or De-
humidification Mode Only)
selected speed until the indoor coil reaches 44 F. At that time, the compressor and outdoor fan will restart.
INDOOR COIL
(Heat Pump Systems Only) If indoor coil temperature is greater than or equal to 135 F, the outdoor fan shuts down. The outdoor fan will restart automatically when the indoor coil temperature drops to 120 F.
TROUBLESHOOTING
See Table 12 and Fig.
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