Ruud air conditioners troubleshooting

The trademark Ruud (USA) is one of the most famous manufacturers of roof-top air conditioners. Its history began in the 1880, when Edwin Ruud, a young engineer from Norway arrived to the United States and created his first successful automatic water heater. The best practices of Ruud in the manufacture of roof-top units led to a new range of devices with additional features and improved performance. In particular, see the troubleshooting table below to solve possible problems with Ruud equipment.

Unit will not run• Power off or loose electrical connection• Check for correct voltage at line voltage connections in condensing unit.
• Thermostat out of calibration set too high• Reset.
• Defective control board• Check control board diagnostic codes.
• Blown fuses/tripped breaker• Replace fuses/reset breaker.
• Transformer defective• Check wiring. Replace transformer.
• High-pressure control open• Reset. Also see high head pressure remedy. The highpressure control opens at 610 PSIG.
• Miswiring of communications (communication light on continuously)• Check communication wiring.
Outdoor fan runs, compressor doesn't• Run or start capacitor defective• Replace.
• Start relay defective• Replace.
• Loose connection• Check for correct voltage at compressor. Check and tighten all connections.
• Compressor stuck, grounded or open motor winding, open internal overload.• Wait at least 3 hours for overload to reset. If still open, replace the compressor.
• Low-voltage condition• Add start kit components.
Insufficient cooling• Improperly sized unit• Recalculate load.
• Improper indoor airflow• Check. Should be approximately 400 CFM per ton.
• Incorrect refrigerant charge• Charge per procedure attached to unit service panel.
• Air. noncondensibles, or moisture in system• Recover refrigerant. Evacuate and recharge. Add filter drier.
Compressor short cycles• Incorrect voltage• At compressor terminals, voltage must be ± 10% of nameplate marking when unit is operating.
• Defective overload protector• Replace. Check for correct voltage.
• Refrigerant undercharge• Add refrigerant.
Registers sweat• Low indoor airflow• Increase speed of blower or reduce restriction. Replace air filter.
High head, low vapor pressures• Restriction in liquid line, expansion device, or filter drier• Remove or replace defective component.
• Bad TXV• Replace TXV.
High head, high or normal vapor pressure Cooling mode• Dirty outdoor coil• Clean coil.
• Refrigerant overcharge• Correct system charge.
• Outdoor fan not running• Repair or replace.
• Air or noncondensibles in system• Recover refrigerant. Evacuate and recharge.
Low head, high vapor pressures• Bad TXV• Replace TXV.
• Bad compressor• Replace compressor.
Low vapor, cool compressor, iced indoor coil• Low indoor airflow• Increase speed of blower or reduce restriction. Replace air filter.
• Operating below 65°F outdoors• Add Low Ambient Kit.
• Moisture in system• Recover refrigerant. Evacuate and recharge. Add filter drier.
High vapor pressure• Excessive load• Recheck load calculation.
• Defective compressor• Replace.
Fluctuating head and vapor pressures• TXV hunting• Check TXV bulb clamp. Check air distribution on coil. Replace TXV.
• Air or noncondensibles in system• 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.
High superheatLow chargeCheck system charge.
(greater than 15°F [-9°C] at coil)Faulty metering deviceRestricted cap tube. TEV (TXV)
Power element superheat out of adjustment internally
Foreign matter stopping flow
High internal loadHot air (attic) entering return
Heat source on: miswired or faulty control
Restriction in liquid lineDrier plugged.
Line kinked.
Low head pressureLow charge
Operating in low ambient temperatures
Suction or liquid line subjected to high heatHot attic
sourceHot water line
Low line voltageLoose wire connectionsCheck wiring.
Power company problem, transformerHave problem corrected before diagnosis continues.
Undersized wire feeding unitCorrect and complete diagnosis.
High line voltagePower company problemHave problem corrected.
High head pressureOverchargeCheck system charge.
Dirty heat pump coilClean coil.
Faulty or wrong size heat pump fan motorReplace fan motor.
Faulty fan blade or wrong rotationReplace fan blade.
Replace with correct rotation motor.
Recirculation of airCorrect installation.
Additional heat sourceCheck for dryer vent near unit.
Check for recirculation from other equipment.
NoncondensiblesRecover refrigerant. Evacuate and recharge system.
Equipment not matchedCorrect mismatch.
Short cycling of compressorFaulty pressure controlReplace pressure control.
Loose wiringCheck unit wiring.
ThermostatLocated in supply air stream
Differential setting too close
Customer misuse
TEVInternal foreign matter
Power element failure
Valve too small
Distributor tube/tubes restricted
Distributor tubeRestricted with foreign matter
I.D. reduced from previous compressor failure
Low chargeCheck system charge.
Low evaporator airflowDirty coil
Dirty filter
Duct too small or restricted
Faulty run capacitorReplace.
Faulty internal overloadReplace compressor.
Faulty Compressor ValvesFast equalization/Low pressure differenceReplace compressor and examine system to locate reason.
Voltage present on load side of compressor contactor and compressor won't runCompressor start componentsCheck start capacitor.
Check potential relay.
Run capacitorCheck with ohmmeter
Internal overloadAltov/ time to reset.
Compressor windingsCheck for correct ohms.
Voltage present on line side of compressor contactor onlyThermostatCheck for control voltage to contactor coil.
Compressor control circuitHigh-pressure switch
Low-pressure switch
Ambient thermostat
Solid-state protection control or internal thermal sensors
Compressor timed off/on control or interlock
No voltage on line s»de of compressor contactorBlown fuses or tripped circuit breakerCheck for short in wiring or unit.
Improper wiringRecheck wiring diagram.
Improper voltageHigh voltageWrong unit
Power suppty problem
Low voltageWrong unit
Power suppty problem
Wiring undersized
Loose connections
Single Phasing (3 phase)Check incoming power and fusing.
Liquid in the compressor shellFaulty or missing crankcase heaterReplace crankcase heater.
Too much liquid in systemIncorrect pipingCheck piping guidelines.
OverchargeCheck and adjust charge.
MoisturePoor evacuation on installation or during serviceIn each case, the cure is the same. Recover refrigerant. Add filter drier, evacuate, and recharge.
High head pressureNoncondensibles air
Unusual head and suction readingsWrong refrigerant or mixed refrigerants
Foreign matter copper filingsCopper tubing cuttings
Copper oxideDirty copper piping or nitrogen not used when brazing
Welding scaleNitrogen not used during brazing
Soldering fluxAdding flux before seating copper partway
Excess soft solderWrong solder material
Compressor failuresLine tubing too largeReduce pipe size to improve oil return.
Low suction pressureLow chargeCheck system charge.
Refrigerant leaksRepair and recharge.
Cold, noisy compressor SluggingDilution of oil with refrigerantObserve piping guidelines.
Noisy compressorMigrationCheck crankcase heater.
Cold, sweating compressorFloodingCheck system charge.
Low loadReduced airflowDirty filter
Dirty coil
Wrong duct size
Restricted duct
Thermostat settingAdvise customer.
Short cycling ofFaulty highor low-pressure controlReplace control.
compressorLoose wiringCheck all control wires.
ThermostatIn supply air stream, out of calibration
Customer misuse
On start-upIncorrect pipingReview pipe size guidelines.
TEV hunting when runningFaulty TEVReplace TEV.

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