What Are the Causes of Overload Reading on Central Air Conditioning?

Compressor Motor

• One possible reason that you may get an overload reading when checking the electrical components of your central air conditioner is that the compressor motor may be bad and needs to be replaced. You can determine this by using a basic multimeter to check the three terminals labeled C, R, and S. These are the standard designations on most air-conditioning units. If the resistance reading is significantly higher than 30 ohms, you likely have a compressor motor issue.

Relays

• Closely related to the compressor motor and compressor operation, the motor relays and motor overload switches are the devices in the air conditioner that trip when there is a problem related to the compressor or motor. These relays are designed to keep the system working properly by shutting down during a surge. They trip at the point of a preset overload to prevent a complete system meltdown.

Capacitors

• An overload reading may be the result of your air conditioner's start or run capacitors. The capacitors are responsible for storing an electrical charge; they provide extra torque at start-up or during the operation of the air conditioner as needed. If the capacitors on an air conditioning unit go bad, the rest of the system must work harder than it is able to and may force a shutdown, amounting to a system overload. If this is the case, the cost is minimal and replacement is fairly simple.

Other Problems

• Regardless of whether the issue is the capacitors, the compressor or the motor, the real root of the problem can be any number of different issues that cause these parts to fail. Old and aging compressor motors are, for instance, more likely to have trouble starting and can cause an overload. Various electrical motors within the air conditioner, aside from the compressor motor, may also cause the system to fail due to its inability to draw enough power. Unbalanced refrigerant pressures and low-line voltage can also be contributing factors.