Why is my AC not turning on in my house?

Author: Dr. Annette Gleichner I  |  Last update: Thursday, May 1, 2025

If your home's central air isn't working at all, check the main electrical panel in your house. It could just be a tripped breaker or blown fuse. If that's the issue, just reset the breaker or replace the blown fuse. Your thermostat setting could be another reason why your central air isn't working.

Why is my AC not kicking on?

The main reasons your AC unit outside is not turning on could be something that has tripped the circuit breaker, something is blocking the fan's airflow, or the condensing unit is damaged. Other potential issues could be the thermostat isn't set correctly or the compressor could be malfunctioning.

Why is my thermostat on but AC not running?

Checking basic thermostat settings, power supply components, and air filter conditions are essential to troubleshoot why an AC unit isn't turning on. More advanced issues requiring professional attention include faulty wiring, a malfunctioning outdoor unit, a bad capacitor, or incorrect thermostat calibration.

Why is my AC not switching on?

Check your circuit breaker if your AC is not turning on. If the circuit breaker has tripped, you will need to reset it for the air conditioner to start working again. If your circuit breaker does trip, here's how to reset it: Locate your main circuit breaker and switch it back to the "On" position.

How do I get my AC to kick on?

Follow these steps.
  1. Step 1: Check the thermostat. Make sure that your thermostat is set to "cool" and not "heat" (if it's set to heat, your AC won't turn on no matter what). ...
  2. Step 2: Check the air filter. ...
  3. Step 3: Check the circuit breakers. ...
  4. Step 4: Clear the condensate drain.

Home AC Blowing Warm Air TROUBLESHOOTING Step BY Step REPAIR Quick Easy Fix

Can resetting the breaker fix AC?

In the majority of cases, your AC system will return to functioning normally after this breaker reset. It's important to know that this isn't an instant fix and may take up to an hour to get back up and running as normal again.

How do I force start AC?

How to Reset an Air Conditioner in Four Steps
  1. Power down your AC. Turn off the power at the circuit breaker. ...
  2. Press the reset button. Most models require you to hold the button down for 3-5 seconds before releasing.
  3. Restore power to your AC. ...
  4. Listen and monitor.

How do I know if my thermostat is bad?

7 Ways to Tell Your Thermostat Is Broken
  1. The Thermostat Has No Power. ...
  2. The AC or Furnace Won't Turn On. ...
  3. The Heater or AC Won't Turn Off. ...
  4. The Thermostat Reading Doesn't Match the Room Temperature. ...
  5. The Thermostat Doesn't Respond. ...
  6. The HVAC System Is Short Cycling. ...
  7. The Thermostat Forgets Programmed Settings.

What causes your AC to stop working?

Inadequate Maintenance. Dirty Filters and Coils: Can cause the system to malfunction and lead to premature compressor or fan failure. Solution: Change filters regularly. Ensure filters fit securely to prevent air bypass.

Why is my central AC not turning on?

It Won't Turn On

Check your breaker box for a blown breaker or tripped fuse. You may be able to fix this AC issue with the flip of a switch. If that doesn't do the trick, check the wiring in your thermostat. A loose or frayed wire could also prevent your unit from turning on.

Can a bad thermostat cause AC not to work in my house?

Absolutely. While it may seem like a small part of your HVAC system, the thermostat plays a crucial role in ensuring your home stays cool and comfortable.

Is there a reset button on AC thermostat?

Most modern thermostats will have a clearly marked reset button inside the panel. It's usually small and recessed, so you might need a pointed object like a paperclip to press it.

Why wont my AC kick back on?

Resetting your thermostat is often all that's necessary to get it working again. A tripped circuit breaker is another common reason why your AC won't turn on. Using too many appliances at once can trip the circuit breaker. This is also common when there are power surges after a big storm.

What is the first thing to check when the AC stops working?

Check these issues when the unit won't kick on: Check the thermostat and adjust the settings if it isn't set to Cool and an appropriate temperature setting to call for cooling. Examine the house circuit breakers for the AC unit and reset any tripped breakers. Check the air filter and replace the filter if it's dirty.

How to tell if an AC fuse is blown?

Blowing the fuse cuts the power to the unit to prevent electrical damage. If your AC has shut down and won't start again, especially if you've noticed odd electrical behavior immediately before the shutdown, chances are the fuse has done its job and will need to be replaced.

How do you check the AC thermostat?

Connect the red wire of the multimeter to the red wire of the thermostat and the black wire of the multimeter to the black or white wire from the thermostat. A functioning thermostat should have readings close to zero or zero. If not, there is a problem with the thermostat.

How much does it cost to replace a thermostat?

Replacing a Thermostat. You'll pay between $15 and $300 for the unit in addition to labor ($65 to $100 per hour) to replace an old thermostat with a new one. However, installing a brand-new thermostat is more involved and, therefore, more expensive.

How do I know if my AC is broken?

10 Signs Your Air Conditioner Needs Repair or Replacement
  1. Air Conditioning System is Blowing Warm Air. ...
  2. AC Thermostat is Not Working. ...
  3. Little Air Blows Out of Vents. ...
  4. Loud Noise Inside of the AC Unit. ...
  5. Strange Odors When AC Turned On. ...
  6. Not Enough Humidity Removed By the AC. ...
  7. Problems with the AC Are Occurring More Often.

How do I get my air conditioner to kick on?

Eight Reasons Why Your AC Won't Turn On-And What to Do
  1. 1) Check the Thermostat. ...
  2. 2) Check the Air Filter. ...
  3. 3) Check the Circuit Breaker. ...
  4. 4) Check the Indoor Shutoff Switch. ...
  5. 5) Check the Outdoor Shutoff Switch. ...
  6. 6) Find the AC's Reset Button. ...
  7. 7) Inspect the AC for Ice Buildup. ...
  8. 8) Ensure the Condensate Drain Isn't Clogged.

Why is my thermostat not turning on the AC?

Air Conditioner Won't Turn On

Be sure the thermostat is set to “cool” mode and the temperature is set low enough to call for the A/C to come on. Look for a tripped circuit breaker or blown fuse. If you're satisfied that the system is getting power, a faulty thermostat may be preventing the system from turning on.

How do I reset my air conditioner?

Reset the AC Using the Isolation Switch

The isolation switch looks like an ordinary light switch with a knob. Once you locate it, turn the knob to the off position and leave it for at least 30 minutes up to an hour. This will allow the electrically operated components in the AC to reset.

Why wont my central air kick on?

There are a number of reasons why your AC unit may stop working unexpectedly, including electrical problems, blockages, thermostat issues, and more. Troubleshooting includes checking your circuit breakers, thermostat settings, and replacing your air filters.

How long to leave AC off to reset?

Shut off your system by hitting the isolation switch, wait 30 to 60 minutes and then turn it back on. This manual reboot fully disconnects your AC unit from power, allowing all electrical components to reset.

Where is the AC breaker located?

Circuit breakers can be found in homes, businesses, and industrial facilities. They are typically located in the main electrical panel, which is typically located in the basement or garage.

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