Testing The User Interface And Electronic Control Board; Thermistors Description - Friedrich Kuhl KCQ06A10A Service Manual

WARNING
ELECTRIC SHOCK HAZARD
Turn off electric power before service or
installation. Extreme care must be used, if it
becomes necessary to work on equipment with
power applied.
Failure to do so could result in serious injury or
death.

Testing the User Interface and Electronic Control Board

If the User Interface does not turn on:
1. Make sure the unit has the proper voltage and that it is turned on. Check power at Terminals L1 and L2.
(refer to Electronic Control Board Identification, Fig 707
2. Disconnect the User Interface's wire harness on the control board.
3. Using a voltmeter, check the outer pins on the user interface port of the elctronic control board . There
should be 24VDC. (refer to Electronic Control Board Identification, Fig 707)
4. If there is no voltage, replace the electronic control board.
5. If 24 VDC is present replace the User Interface and/ or the ribbon cable.

Thermistors Description

The KUHL units have 4 sensors (Thermistors). Each thermistor is color coded and has a differnt function.
1. Indoor Coil (Yellow) - located on the evaporator coil next to the power board
2. Outdoor Coil (Blue) - located on the condensor coil.
3. Discharge Air (Black) - located on the front of the unit in the discharge air port.
4. Ambient Air (White) - located o nt he front of the unit in front of the air intake
Thermistor Testing
1. Gain access to Electronic Control Board.
2. Locate thermistor plug and disconnect from Control Board. (refer to Control Board Identification, FIg 707)
3. Check for proper resistance. (refer to Thermistor Resistance values, Fig 707)
4. If thermistor is out of tolerance, replace thermistor.
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COMPONENTS TESTING