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SECTION 9. TROUBLE-SHOOTING CHART
WARNING: Disconnect all power to unit before servicing. Failure to shut off power can cause electrical shock resulting
in personal injury or death.
Symptom
Unit will not operate
Outdoor fan on;
Compressor off
Too little cooling
Compressor
operates
in
short cycles
High head pressure;
Low suction pressure
High head pressure;
Normal suction pressure
Low head pressure;
High suction pressure
Low suction pressure;
Compressor cool;
Ice on indoor coil
High suction pressure;
Or
fluctuating
head
and
suction pressures
Pulsing noise at expansion
device or liquid line
Registers sweat
Installer's Information Manual
Possible Cause
•
Power disconnected or loose connection
•
Blown fuse / breaker tripped
•
Thermostat out of calibration – set too high
•
Contactor defective
•
Transformer defective
•
High pressure control open (if provided)
•
Run or start capacitor defective
•
Start relay defective
•
Loose wire
•
Compressor stuck, grounded or open motor
winding, open internal overload
•
Low voltage condition
•
Improperly sized unit
•
Improper indoor airflow
•
Incorrect refrigerant charge
•
Air, non-condensibles or moisture in system
•
Incorrect voltage
•
Defective overload protector
•
Refrigerant undercharge
•
Restriction in liquid line, expansion device or filter
drier
•
Lack of sufficient indoor airflow
•
Dirty outdoor coil
•
Refrigerant overcharge
•
Outdoor fan not running
•
Air or non-condensibles in system
•
Expansion device stuck in open position
•
Defective compressor valves
•
Low indoor airflow
•
Operating below 65degF outdoors
•
Moisture in system
•
Excessive load
•
Defective compressor
•
TXV hunting
•
Air or non-condensibles in system
•
Air or non-condensibles in system
•
Low indoor airflow
Correction
•
Check voltage at contactor in condensing unit
•
Replace fuses / reset breaker
•
Reset
•
Check for 24VAC at contactor coil – replace if
open
•
Check wiring – replace transformer
•
Reset – see high pressure correction (high
pressure control opens at 450 psig)
•
Replace
•
Replace
•
Check for correct voltage at compressor –
check and tighten all connections
•
Wait at lease 2 hours for overload to reset; if
still open, replace the compressor
•
Add start kit components
•
Recalculate load
•
Check – should be approximately 400 CFM
per ton
•
Charge per procedure in installation manual
•
Recover refrigerant, evacuate and recharge,
replace filter drier
•
At compressor terminals, voltage must be +/-
10% of nameplate marking when unit is
operating
•
Replace – check for correct voltage
•
Add refrigerant
•
Remove or replace defective component
•
Clean/check filters, registers, or evaporator
coil that may cause a restriction.
•
Clean coil
•
Correct system charge
•
Repair or replace
•
Recover refrigerant, evacuate and recharge
•
Replace expansion device
•
Replace compressor
•
Increase speed of blower or reduce restriction
– replace air filter
•
Add low ambient kit
•
Recover refrigerant – evacuate and recharge
– replace filter drier
•
Recheck load calculation
•
Replace
•
Check TXV bulb clamp – check air distribution
on coil – replace TXV
•
Recover refrigerant, evacuate and recharge
•
Recover refrigerant, evacuate and recharge
•
Increase speed of blower or reduce restriction
– replace air filter
Page 9
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