Top 4 Reasons Your Air Conditioner Won't Turn On: 2025

Almost nothing can be more excruciating than an AC that won’t turn on in the middle of summer. Sometimes, air conditioning problems have easy fixes. Checking basic issues may restore cooling in your home right away.

This video outlines some initial troubleshooting steps to take when your AC system stops cooling.

Understanding the most common air conditioner failures can help you know what to check when your central air conditioner quits working. When basic troubleshooting doesn’t help you fix your air conditioner, it’s time to schedule service. The HVAC experts at Sears Home Services can quickly troubleshoot your air conditioner to get it running smoothly again.

Use this list of common air conditioning failures to help you identify some basic troubleshooting steps you can take before scheduling service.

1. No Power

Check the house circuit breaker for your air conditioner. Reset the house circuit breaker if it's tripped. Because it’s sometimes difficult to tell whether the house circuit breaker tripped, shut off the breaker then turn it back on. If your air conditioner still isn’t getting power after resetting the house circuit breaker, it’s time to schedule service.

2. Themostat Won’t Work

Some thermostats use batteries. Replace the thermostat batteries if they’re dead.

If the thermostat has power, check its settings. Make sure that your air conditioner thermostat is set to Cool and the temperature setting is low enough to call for cooling.

If you suspect that the thermostat isn’t working properly, replace it with a new one if you’re confident that you complete that DIY repair yourself. Follow the steps in our How to replace a heating and air conditioning system thermostat repair guide to install a new thermostat.

3. Outside Condenser Unit Has No Power

When the blower on the inside unit of your central air conditioner works but it blows warm air, the outside condenser unit may not be getting power.

In many homes, the outside condenser unit has a separate house circuit breaker from the inside unit. Check the house circuit breaker for the outside condenser unit and reset the breaker if it’s tripped. If it doesn’t appear to be tripped, shut the breaker off then turn it back on because it’s often hard to tell when a circuit breaker is tripped.

If the outside condenser unit still has no power after resetting the house circuit breaker, check the disconnect switch for the outside unit. That switch is attached to the side of your home close to the condenser unit. Turn that switch on if you find it in the off position.

If you’re unable to restore power to the outside unit, then it’s time to schedule service.

4. Drain Pipe Is Clogged

A common cause for many air conditioners to quit working is a clogged drain pipe. When the drain pipe that carries condensate water to the outside of your home clogs, water backs up and trips the drain float switch. You’ll also likely see or hear water dripping from under the inside air conditioner unit when the drain pipe clogs up. You won’t see water dripping from the end of the drain pipe outside your home.
The air conditioner control board shuts down the air conditioner when the float switch trips. Read our Sears Tech Tip for Keeping Your AC Running article (with video) to see how you may be able to restore cooling when your air conditioner shuts down because the drain pipe is clogged.

When all basic troubleshooting that you’ve tried doesn’t fix your AC problem, schedule service through our Sears Home Services website. You’ll be able to schedule same day or next day HVAC repair appointments in many areas.

To continue improving our HVAC repair service, Sears Home Services is hiring technicians across the country. Explore HVAC Technician careers and apply to join the nation’s largest home improvement company.