Product data

SERVICE – High Wall Systems
WARNING:
When servicing unit, turn off all electric power to unit to avoid shock hazard or injury from rotating parts.
CAUTION:
Do not vent refrigerant to atmosphere when servicing unit. Recover refrigerant during system repair or unit
removal.
DIAGNOSTIC CODES
This unit is equipped with a microprocessor control, which continuously monitors the operation of the unit. If an
operational fault is detected, a fault is indicated by the flashing of the green ‘‘UNIT ON’’ light on the front of the fan coil
unit. A red LED (light-emitting diode) indicator light, located on the control board in the control box of the indoor unit, will
emit a flash code, which can be used to troubleshoot a system problem. The control will continue to monitor the unit and, if
the conditions that cause the fault are cleared, the unit will return to normal operation. If the fault code is present for 5
cycles of the unit, the unit will be locked out and the alarm is indicated by the flashing of the green ‘‘UNIT ON’’ light on
the front of the fan coil unit. 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 indicates that a fault has been detected See Trouble
Shooting & Fault Code Section #27 for indicators. If the system does not operate and the LED indicator does not flash,
either the power to the control board is off, or the control board has failed.
NOTE: If the LED light continuously flashes on for one second, then off for one second, the control is functioning
properly and no fault is present.
SYSTEM TESTS
System tests listed below are performed continuously by the microprocessor. If a fault is indicated, then the system allows
only limited operation until the problem is resolved. If the problem resolves itself, then the code is cleared and operation
resumes.
Thermistor Tests
Each thermistor is tested for high limit out of range (shorted condition) and low limit out of range (open condition). If the
thermistor is out of range, the fault status indicator comes on and the LED flashes the appropriate fault code.
Thermistors
Proper thermistor location and correct temperature sensing are critical to unit operation. Good thermal contact is also
required. Thermistor cable assemblies are provided with fan coil units to run between indoor and outdoor units. High
voltage and thermistor cable assemblies should 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 d.c. voltage across the two thermistor connections.
See Thermistor Properties Table #10
Compressor Failure
If the System is in Cooling or Dehumidification Mode after 5 minutes of operation, if the temperature of the indoor coil is
not 4° F less than at the time the call for cooling started, then a compressor failure is indicated on the remote controller
LCD display. If the System is in Heat Pump Heating Mode after 5 minutes of operation, if the temperature 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
If the System is in Cooling or Dehumidification Mode after 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 after 5 minutes of operation, if the temperature indicated by the outdoor coil is 4° F more than at the
time the call for heating started, then a reversing valve failure is indicated.
SYSTEM SAFETIES AND INTERLOCKS
Indoor Fan Failure
If the indoor fan rpm shows greater than 800 rpm for 30 seconds with the fan in the off mode, then this test indicates an
indoor fan failure. Also, if the indoor fan rpm is greater than 1700 rpm for 30 seconds, then this test indicates an indoor
fan failure. MORE ON NEXT PAGE