Ruud RP13, Installation Instructions Manual

43

DIAGNOSTICS

General Troubleshooting Chart

WARNING:

 Disconnect all power to 

unit before servicing. Contactor may break only one 

side. Failure to shut off power can cause electrical 

shock resulting in personal injury or death.

SYMPTOM

POSSIBLE CAUSE

REMEDY

Unit will not run

•  Power o

ff

  or loose electrical connection

•  Thermostat out of calibration – set too high

•  Defective control board

•  Blown fuses/tripped breaker

•  Transformer defective

•  High-pressure control open 

•  Miswiring of communications (communication 

light on continuously)

•  Check for correct voltage at line voltage connections in 

condensing unit.

•  Reset.

•  Check control board diagnostic codes.

•  Replace fuses/reset breaker.

•  Check wiring. Replace transformer.

•  Reset. Also see high head pressure remedy. The high-

pressure control opens at 610 PSIG.

•  Check communication wiring.

Outdoor fan runs, 

compressor doesn't

•  Run or start capacitor defective

•  Start relay defective

•  Loose connection

•  Compressor stuck, grounded or open motor 

winding, open internal overload.

•  Low-voltage condition

•  Replace.

•  Replace.

•  Check for correct voltage at compressor. Check and 

tighten all connections.

•  Wait at least 3 hours for overload to reset. If still open, 

replace the compressor.

•  Add start kit components.

Insu

ffi

  cient cooling

•  Improperly sized unit

•  Improper indoor air

fl

 ow

•  Incorrect refrigerant charge

•  Air, noncondensibles, or moisture in system

•  Recalculate load.

•  Check. Should be approximately 400 CFM per ton.

•  Charge per procedure attached to unit service panel.

•  Recover refrigerant. Evacuate and recharge. Add 

fi

 lter 

drier.

Compressor short 
cycles

•  Incorrect voltage

•  Defective overload protector

•  Refrigerant undercharge

•  At compressor terminals, voltage must be ± 10% of 

nameplate marking when unit is operating.

•  Replace. Check for correct voltage.

•  Add refrigerant.

Registers sweat

•  Low indoor air

fl

 ow

•  Increase speed of blower or reduce restriction.

Replace air 

fi

 lter.

High head, low vapor 

pressures

•  Restriction in liquid line, expansion device, or 

fi

 lter drier

•  Bad TXV

•  Remove or replace defective component.

•  Replace TXV.

High head, high 

or normal vapor 

pressure – Cooling 

mode

•  Dirty outdoor coil

•  Refrigerant overcharge

•  Outdoor fan not running

•  Air or noncondensibles in system

•  Clean coil.

•  Correct system charge.

•  Repair or replace.

•  Recover refrigerant. Evacuate and recharge.

Low head, high vapor 

pressures

•  Bad TXV

•  Bad compressor

•  Replace TXV.

•  Replace compressor.

Low vapor, cool 

compressor, iced 

indoor coil

•  Low indoor air

fl

 ow

•  Operating below 65°F outdoors

•  Moisture in system

•  Increase speed of blower or reduce restriction. 

Replace air 

fi

 lter.

•  Add Low Ambient Kit.

•  Recover refrigerant. Evacuate and recharge. Add 

fi

 lter 

drier.

High vapor pressure

•  Excessive load

•  Defective compressor

•  Recheck load calculation.

•  Replace.

Fluctuating head and 

vapor pressures

•  TXV hunting

•  Air or noncondensibles in system

•  Check TXV bulb clamp. Check air distribution on coil. 

Replace TXV.

•  Recover refrigerant. Evacuate and recharge.

Gurgle or pulsing 

noise at expansion 

device or liquid line

•  Air or noncondensibles in system

•  Recover refrigerant. Evacuate and recharge.

Diagnostics