Turn On the Power to Your Central Air Conditioner

You turned off the power to your central air conditioner last autumn to lengthen the life of the heater that vaporizes the refrigerant and to save energy. Now, turn it on a day before you plan to start cooling the house.

By turning on the power to your central AC 24 hours before flipping the switch on the thermostat to "Cool" (which activates the compressor), you give the system time to convert the refrigerant from a liquid to a gas. Otherwise, the compressor tries to pump the liquid, which can damage the compressor.

Time — 5 minutes
Difficulty — Easy
Expertise — None
Frequency — Once a year
Where — All US

Steps

1. Turn on the power to the air conditioning system at the main electrical panel either by reinstalling the fuses that control the AC or by flipping the circuit breaker.
2. If your AC has an outdoor shutoff close to the outdoor unit, flip it to the "On" position.
3. If your furnace has a humidifier attached to it, check whether the humidifier has a damper where it meets the duct. If the damper is open, close it to help your AC run more efficiently.

Tips and Warnings

• The compressor in your AC is designed only to pump the refrigerant when it is a gas. Over the winter, the refrigerant in your system becomes a liquid — which your compressor can't pump — and combines with the oil in your compressor. When you turn on the power to your AC, the heater built into your compressor separates the refrigerant from the oil and boils the refrigerant into a gas.
• Never use your AC when the outside temperature is below 65°F (18°C). You can damage the compressor.
• Having a professional inspect and service your AC increases the life of the unit and prevents breakdowns. Now is a good time to schedule service.