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COOLING ONLY ROOM AIR CONDITIONERS: TROUBLESHOOTING TIPS
noitcA esuaC elbissoP melborP
Compressor
does not run
Low voltage
Check voltage at compressor. 115V & 230V
units will operate at 10% voltage variance
T-stat not set cold enough or
inoperative or electronic control
board is bad
Set t-stat to coldest position. Test t-stat &
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 & resistance
Open overload Test overload protector & replace if inoperative
Open capacitor Test capacitor & replace if inoperative
Inoperative system switch,
thermistor or electronic board
Test for continuity in all positions. Replace if
inoperative switch or electronic board.
Broken, loose or incorrect wiring
Refer to appropriate wiring diagrams to check
wiring
noitcA esuaC elbissoP melborP
Fan motor
does not run
Inoperative system switch Test switch & replace if inoperative
Broken, loose or incorrect wiring Refer to applicable wiring diagram
Open capacitor Test capacitor & replace if inoperative
Fan speed switch open Test switch & replace if inoperative
Inoperative fan motor
Test fan motor & replace if inoperative (be sure
internal overload has had time to reset)
noitcA esuaC elbissoP melborP
Does not cool or
only cools slightly
Undersized unit Refer to industry standard sizing chart
T-stat open or inoperative
Thermistor or electronic board is bad, Set to coldest position. Test t-stat or electronic
control board & replace if necessary.
Dirty fi launaM s’renwO ni dednemmocer sa naelC retl
Dirty or restricted condenser or
evaporator coil
Use pressure wash or biodegradable cleaning
agent to clean
Poor air circulation Adjust discharge 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 & make repair
Compressor not pumping properly
Check amperage draw against nameplate. If
not conclusive, make pressure test
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