Possible Reasons Why Air Conditioner Would Not Turn On

If your home is not as cool as you want it to be, or if it is not cooling at all, the problem may be with your air conditioner. That said, if you are unsure what to look out for, below are some of the possible reasons why your unit would not turn on.

1. Check Your Thermostat Settings

The thermostat should be set to “cool,” and the temperature should be lower than the current room temperature. If the fan is set to “auto,” it will only run when the air conditioner is cooling air. The “on” setting means that the fan will keep running even when the AC is off.

If the thermostat is blank, it may need new batteries, or the circuit breaker associated with it may have tripped.

2. Check Your Residential Circuit Breaker Panel

A power surge is a sudden increase in electricity that can cause a circuit breaker to trip. This stops the flow of electricity and can prevent your AC from turning on.

If a circuit breaker has tripped, it will no longer allow electricity to flow through it. To reset a tripped breaker, simply flip it back to the “on” position.

3. Ensure That Your HVAC System’s Power Switches Are On

Central air conditioners have two power switches: one for the indoor unit and one for the outdoor unit. Both switches must be in the “on” position for the unit to work.

You can find the switch for the indoor unit of your HVAC system near your furnace or air handler. The switch for the outdoor unit is usually located next to the outdoor unit, in a metal box outdoors.

4. Check If the Unit’s Air Filter Is Dirty

A clogged air filter will make it harder for your AC unit to circulate air, which could lead to the unit overheating and shutting off. To avoid this, aim to replace your air filter every three months.

You should replace your air filter if you don’t remember the last time you did it or if it looks dirty. Keep a few filters around so you can replace them anytime.

5. See If Any Plants or Debris Are Crowding around the Outdoor Unit

Make sure that there is nothing blocking the airflow around your AC unit, such as landscaping, leaves, or dirt. Debris can cause your unit to overheat and turn off, so it’s important to keep the area clear. There should be at least two feet of clearance around the unit and several feet of vertical space. Outdoor AC units need to have enough space around them so that the heat they release can dissipate properly.

6. Try to Reset the Unit

If your air conditioner starts behaving strangely after a power surge, it may just need a hard reset. Check your system’s owner’s manual for the correct way to reset your system to avoid making the problem worse.

Resetting your air conditioner can fix many common problems, like lost cooling, overheating, and even loud noises.


Overall, there are several possible reasons why your air conditioner would not turn on. Some of these reasons may be due to a problem with the air conditioner itself, while others may be due to a problem with the surrounding environment or with your home’s electrical system. If your air conditioner is not turning on, be sure to troubleshoot the problem and identify the root cause before attempting any repairs.

If you are looking for a company that deals with air conditioning repairs in Calgary and Edmonton, AB, look no further than our expertise here at Legacy Heating. We specialize in HVAC systems for residential new home construction (RNC) and installation and replacement of furnaces, air conditioners, air cleaners, thermostats, humidifiers, etc. Call us today and let us check the condition of your AC unit in no time!

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