Wallmaster Service Manual (2010)
35
COOLING ONLY ROOM AIR CONDITIONERS: TROUBLESHOOTING TIPS  
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Compressor runs  
for short periods  
only. Cycles on 
overload
Overload inoperative. Opens too
soon
 Check operation of unit. Replace overload if
 system operation is satisfactory 
Compressor restarted before 
system pressures equalized 
Control board’s default of 3 minutes
delay inoperative. Replace board.
Low or fl uctuating voltage 
 Check voltage with unit operating. Check for
 other appliances on circuit. Air conditioner 
 should be in a dedicated circuit with proper 
 voltage & fused separately 
Incorrect wiring   Refer to appropriate wiring diagram 
Shorted or incorrect capacitor 
 Test capacitor and replace as needed.
Restricted or low air fl ow through 
condenser coil or evaporator coil 
 Check for proper fan speed or blocked
 coils. Correct as needed. 
Compressor running abnormally 
hot
 Check for kinked discharge line or restricted
 condenser. Refrigerant overcharge.
Check amperage, connections. 
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Unit does not
turn on
No power
Check power supply, LCD I plug, wire
connection.
Incorrect wiring   Refer to appropriate wiring diagram 
Defective thermistor  Replace thermistor or electronic control board
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Noisy operation 
Poorly installed
 Refer to Installation Manual for proper
 installation 
Fan blade striking chassis   Reposition - adjust motor mount 
Compressor vibrating 
 Check that compressor grommets have not 
 deteriorated. Check that compressor mounting 
 parts are not missing 
Improperly mounted or loose
cabinet parts 
 Check assembly & parts for looseness,
 rubbing & rattling 
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Water leaks into  
the room 
Evaporator drain pan overfl owing   Clean obstructed drain trough 
Condensation forming underneath
base pan 
 Evaporator drain pan broken or cracked.
 Reseal or replace. No chassis gasket installed.
 Install chassis gasket
Poor installation resulting in rain 
entering the room 
 Check installation instructions. Reseal as
 required 
Condensation on discharge grille 
louvers
 Dirty evaporator coil. Use pressure wash
 or biodegradable cleaning agent to clean.
 Environmental phenomena: point supply 
 louvers upward. Put fan on high.
Chassis gasket not installed   Install gasket, per Installation manual 
Downward slope of unit is too
steep inward
 Refer to installation manual for proper
 installation 
Possible Solution
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Possible Solution
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