Recently Moved to a Home & the AC Won't Come On? How to Check the Disconnect Switches

If you recently moved to a new or old home, and the AC won't come on, you might think that there's a serious problem with the cooling system. Although the air conditioner could possibly have a serious issue to fix, it's not always the case. Sometimes, small issues can occur in cooling systems that make it appear as though they're bad, including turned off disconnect switches. Before you panic or call your AC contractor for help, try to fix your AC's problems with the information and tips below.

Why Should You Check the Disconnect Switches?

Every cooling system uses two separate units to operate: an indoor air handler, or furnace, and an outdoor condensing unit. Both units connect to special switches that you can turn off, or disconnect, during emergency situations that might damage your cooling system, such as seasonal storms and electrical problems. The units also rely on the switches for electrical power during everyday use. A number of things can disrupt power to the switches, including accidentally turning them off and power outages.

If the previous homeowner, renter or real estate agent accidentally disconnected the switch inside or outside the house, the entire cooling system won't come on. Sometimes, power outages or fluctuations can inadvertently turn the switches off. If the home's electrical power remained on during showings, it may have happened during one of those times. 

How Do You Check the Disconnect Switches?

The first thing to do is to completely disconnect electrical power to the cooling system by turning it off at the main circuit breaker. Although the cooling system isn't coming on, it could still have electric running through its power switches that may shock your hands when you touch them. You can return power to the system after you check the switches.

Both switches hide inside small, covered boxes that resemble circuit breaker boxes and usually sit close by the units. The switches themselves look similar to breakers or fuses because they convey electrical power in a similar fashion. To access the switches, you'll need to lift up or remove the boxes' covers with clean, dry hands. Because each switch operates in a specific way, you must follow specific steps to check and repair them. It's a good idea that you start with the indoor switch first, then move the outdoor switch.

Enter your indoor air handler's closet, then use a flashlight to examine the face or front surface of the disconnect switch. Flip the switch back and forth to reset it. The switch should face the "on" position when you're done. If you're unsure about this step, read over the user instructions located in the inside paneling of box. After you reset the switch, turn on your cooling system and wait for it to come on.

If the indoor and outside units both come on, you solved the issues. But if only the indoor unit turns on, and the outdoor unit stays off, check the outdoor switch to see if it's on. You'll need to turn off the cooling system's power one more time for safety.

The outdoor switch will generally have the words "on" and "off" on the front of it. If the switch's toggle points in the off position, move it to the "on" position, then return power to the system. If power does reach the outdoor unit, its fan will spin and the motor will start.

If none of these things above happen, contact an AC repair technician through resources like for additional help. A contractor can test the indoor and outdoor units to see if they need repairs, or if you need to replace one or both.