Friedrich Kuhl KCS12B10A Service Manual page 56

COMPLAINT
Fan motor does not run.
Does not cool or only cools
slightly
Unit does not run
Evaporator coil freezes up
Compressor runs continually
& does not cycle off
56
TROUBLESHOOTING
CAUSE
Inoperative system button
Broken, loose or incorrect wiring
Open capacitor
Fan speed button defective
Inoperative fan motor
Undersized unit
Indoor ambient thermistor open or
shorted
Dirty filter
Dirty or restricted condenser or evapo-
rator coil
Poor air circulation
Fresh air or exhaust air door open
Low capacity - undercharge
Compressor not pumping properly
Fuse blown or circuit tripped
Loose or disconnected wiring control
board or other components
The LCDI power cord has tripped (Reset
button has popped out).
Dirty filter
Restricted airflow
Inoperative thermistor
Short of refrigerant
Inoperative fan motor
Partially restricted capillary tube
Excessive heat load
Restriction in line
Thermistor shorted
SOLUTION
Test button & replace user interface if inoperative
Refer to applicable wiring diagram
Test capacitor & replace if inoperative
Replace user interface if inoperative
Test fan motor & replace if inoperative (be sure internal over-
load has had time to reset)
Refer to industry standard sizing chart
See diagnostic codes and replace thermistor if needed.
Clean as recommended in Owner's Manual
Use pressure wash or biodegradable cleaning agent to clean
Adjust discharge louvers. Use high fan speed
Close doors. Instruct customer on use of this feature
Check for leak & make repair
Check amperage draw against nameplate. If not conclusive,
make pressure test
Replace fuse, reset breaker. If repeats, check fuse or breaker
size. Check for shorts in unit wiring & components
Check wiring & connections. Reconnect per wiring diagram
Press and release RESET (Listen for click. Reset button latches
and remains in.) Check that the green LED light is on to resume
operation.
Clean filter (see Routine Maintenance)
Check for dirty or obstructed coil. Clean coil (refer to routine
Maintenance)
Check Diagnostic Codes. Check Thermistors and replace as
necessary.
De-ice coil & check for leak
Test fan motor & replace if inoperative
De-ice coil. Replace capillary tube
Unit undersized. Test cooling performance & replace with
larger unit if needed. See sizing chart.
Check for partially iced coil & check temperature split across
coil
Replace thermistor or electronic control board