The easy explanation for your AC not turning on is a thermostat issue. Double check your thermostat is on, set to “cool,” and that the temperature is set to a few degrees colder than the normal ambient temperature of your home. You may also need to replace the batteries.
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.
Power issues: A tripped circuit breaker or blown fuse in your home's electrical system will prevent your AC from starting. Thermostat problems: Make sure you have your thermostat set to “cool” and the temperature is set below the current temperature in the room.
If your thermostat is set to cool but your AC isn't turning on, there could be several potential causes ranging from a simple tripped breaker to more complex refrigerant or compressor issues. Start with the basics, like checking the thermostat settings and power supply, and work through more detailed troubleshooting.
The thermostat is the central control of your HVAC system, and malfunctioning can prevent the AC and furnace from turning on. This problem can be due to bad wiring connecting the thermostat to the AC and heater, or a thermostat that has reached the end of its life.
Check Your Circuit Breaker
Locate your main circuit breaker and switch it back to the "On" position. Wait 30 seconds and turn on your air conditioner again. If it still doesn't work, you'll need to call a professional for help.
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.
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.
You'll want to have the unit examined for signs of a blown fuse, tripped circuit breaker, broken thermostat, or dirty air filters. Dirty or clogged filters commonly make AC compressors stop working. When it comes to operating your cooling system properly, be realistic with the temperature setting on your thermostat.
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.
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.
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.
A sure sign of a bad AC capacitor is a humming sound from within the access panel. Any humming noises indicate a problem with the air conditioning system or the components of the AC unit. Try turning the power on and off again to see if it was a one-time issue with the motor or a recurring problem.
If your air conditioner won't turn on, try replacing the batteries if the thermostat is battery operated. 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.
Faulty or Malfunctioning Thermostat
If your thermostat clicks repeatedly and your AC doesn't turn on, it usually indicates that the problem is related to the thermostat itself and could be caused by either an issue with the thermostat relay or the system's wiring.
There are a few reasons why this might happen. Some of the simpler causes may be that a vent is closed, or that the thermostat needs fixing. Some more major causes may be that the unit is low on refrigerant, signaling a leak, or that there is a problem with the fan.
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.
A few things may go wrong that cause a thermostat to turn unresponsive: Loss of direct connection to the air handler or compressor. There are separate wires from the thermostat to the parts of the air conditioner, and if one of them frays or breaks, the AC may not turn on (or may not turn off).
While a tripped circuit breaker is often the culprit, other issues could be at play, such as a malfunctioning thermostat, a blocked condensate drain, or even a blown fuse. At Air Repair Pros, our experts have extensive experience diagnosing and repairing AC problems.
A safety switch is located in different places according to the installation of AC. If the air handler is built vertically, it will be usually mounted on the front of the unit, near to the main condensate drain that exits the unit. It will have two wires coming out of it from where float can be removed.