8.3 Troubleshooting Cooling
PROBLEM POSSIBLE CAUSE TO CORRECT
Low voltage. Check for voltage at compressor. 115 volt
and 230 volt units will operate at 10%
voltage variance
Thermostat not set cold enough
or inoperative.
Set thermostat to coldest position. Test
thermostat and replace if inoperative.
Compressor hums but cuts off on
overload.
Hard start compressor. Direct test
compressor. If compressor starts, add
starting components.
Open or shorted compressor
windings.
Check for continuity and resistance.
Open overload. Test overload protector and replace if
inoperative.
Test capacitor and replace if inoperative.
Open capacitor. Test for continuity in all positions.
Inoperative system switch. Replace if inoperative.
Compressor
does not run.
Broken, loose or incorrect wiring. Refer to appropriate wiring diagram to check
wiring.
Inoperative system switch. Test switch and replace in inoperative.
Broken, loose or incorrect wiring. Refer to applicable wiring diagram.
Open capacitor. Test capacitor and replace if inoperative.
Fan speed switch open. Test switch and replace if inoperative.
Fan motor
does not run.
Inoperative fan motor.
Test fan motor and replace if inoperative.
(Be sure internal overload has had time to
reset.)
Undersized unit. Refer to Sizing Charts.
Thermostat open or inoperative. Set to coldest position. Test thermostat and
replace if necessary.
Dirty filter. Clean as recommended in Owner’s Manual.
Dirty or plugged condenser or
evaporator coil.
Use steam or detergents to clean.
Poor air circulation in area being
cooled.
Adjust discharge air louvers. Use high fan
speed.
Fresh air or exhaust air door
open on applicable models.
Close doors. Instruct customer on use of this
feature.
Low capacity – undercharge. Check for leak and make repair.
Does not
cool, or cools
only slightly.
Compressor not pumping
properly.
Check amperage draw against nameplate. If
not conclusive, make pressure test.
Service Manual
Room Air Conditioner with R-410A
Heat Controller, Inc.
30