Problem guide
How to reset an AC unit
A reset clears a tripped breaker or a confused control. It does not fix a failing part.
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Written by HYRE HVAC Research Desk Primary-source research, data analysis and fact checking
The short answer
To reset an AC unit, turn the thermostat to off, switch off the breaker for the outdoor unit (and the indoor unit if separate), wait a few minutes, switch the breakers back on, then set the thermostat to cool. Give the system five minutes to start.
If it runs normally, the reset worked. If the breaker trips again or the problem returns, stop resetting and call a technician.
The reset sequence
Set the mode to off so the system does not try to start while you restore power.
At the main panel, switch off the breaker for the outdoor unit, and the furnace or air handler breaker if you are resetting both.
A few minutes lets pressures in the system equalize and controls fully power down.
Switch them firmly on. A tripped breaker must go fully off before it will reset.
Set a temperature below the room. Wait about five minutes for the start-up delay.
What about a reset button?
Some outdoor units and many ductless systems have a reset or restart button, and some thermostats have a reset in the menu. Use those as the manual describes.
Many central AC outdoor units have no reset button at all; the breaker is the reset. Do not open the outdoor unit’s panel looking for one: the capacitor inside can hold a dangerous charge.
When a reset helps, and when it does not
| Situation | Reset likely to help? |
|---|---|
| Power outage or surge, AC will not restart | Yes |
| Breaker tripped once, no other symptoms | Yes, once |
| Thermostat frozen or unresponsive | Often; try the thermostat reset first |
| Breaker trips again after reset | No: electrical fault |
| Ice on the lines | No: thaw and check filter; see the freezing guide |
| Water in the pan, float switch tripped | No: clear the drain first |
| Outdoor fan not spinning, unit humming | No: likely capacitor or motor |
Stop and call when
Do not keep resetting. Repeated trips heat the wiring.
Do not open the outdoor unit, furnace cabinet or control box. Capacitors can hold a dangerous charge with the power off, and line-voltage work is for a licensed technician.
Turn it off at the breaker and call.
Adding refrigerant, finding leaks or even attaching gauges requires EPA Section 608 certification.
Why repeated resets are a bad idea
A breaker trips to protect the wiring from too much current. A reset into an unrepaired fault, such as a shorted compressor, a failing capacitor or a damaged wire, sends that current through again.
A technician can measure what the system is drawing and find the cause. HyreHVAC publishes no repair prices yet; use the repair cost calculator with your own quote.
After a power outage
When power returns after an outage, many systems wait several minutes before restarting. If the AC does not start after ten minutes, check whether the outage tripped a breaker, then try the reset sequence. Surges can damage control boards and capacitors; if the system stays down, have it checked.
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Questions
How do I reset my AC after a power outage?
Does my AC have a reset button?
How long should I wait to turn the AC back on?
Is it bad to keep resetting the AC breaker?
Will resetting fix my AC not cooling?
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HYRE HVAC Research Desk
Primary-source research, data analysis and fact checking
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