Resistance of a Typical Air Conditioner

Resistance

• Many of the problems that air conditioners have are related to some form of electrical problem. When diagnosing problems with the compressor or other parts of the air conditioner, it might be necessary to ensure that you don't have problems with the electrical resistance. The typical air conditioner will have a resistance of 30 ohms or less. Using a voltmeter that provides a resistance measurement, you can check your air conditioner's resistance to determine whether an electrical issue exists. A reading higher than 30 ohms could indicate an electrical problem.

Cooling

• The cooling effect of the air conditioning unit is produced by the interaction of the compressor with the refrigerants that are sealed within the system. The compressor compresses these refrigerants into liquid form. As the liquid turns back into vapor, it has cooling effect. The cooling effect is then transferred to the air as it blows through the system, resulting in cold air for the home. The action of the compressor requires significant electrical current, but also resists the current in the process.

Troubleshooting

• If you suspect an issue with your air conditioner's compressor, a quick resistance test should reveal the source of your problem. Disconnect the electrical power before performing any tests. Once you do, check the resistance between the motor start and run common terminals. A reading of "zero" suggests that the compressor winding is broken. For the compressor, a reading to the other end of the meter, the "over" reading, indicates that winding has burned through. A reading of "zero" or close to zero probably suggests that it has shorted out.

Replacement

• When the resistance reading on the compressor indicates that it has been burned out, replacement is the only possible solution. The shorting out of the internal wiring and mechanisms of the compressor motor causes the motor to fail to provide the proper pressure needed to create the cooling effect caused by the compression of the refrigerants.