If your outside AC unit is not turning on, one of the most common (and simplest) reasons is an electrical issue like a tripped circuit breaker cutting the power to the unit. Other potential reasons with simple fixes include the thermostat being set incorrectly and the unit being low on refrigerant.
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.
If your outside AC unit is not turning on, it could be a thermostat issue. If your thermostat clicks but the AC does not turn on, you could have an issue with the thermostat itself. Broken thermostats often fail to properly communicate with the rest of your heating and cooling system.
When the outside unit breaks down but the inside unit is running, the culprit may well be a broken compressor in the outside unit. That's typically a major repair, something that might even warrant a system replacement.
It's a small, red button usually located on or around the unit. The button should have a clear 'reset' label. Once you find the button, press it for around three seconds and observe the AC. Check whether the AC kicks on immediately and if it doesn't, press the button again for another three seconds.
In AC systems, the air conditioner reset button is on the outside unit's lower edge, typically close to the ground. Some models have the reset button located behind the service panel, which may require tools to remove. Reset buttons are usually red or yellow with a clear “reset” label.
Common Reasons Why Your Air Conditioner is Not Turning 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.
For AC capacitor replacement, anticipate spending between $150 and $400, depending on the capacitor's type and accessibility. A bad AC capacitor is a fairly minor repair, and most HVAC technicians will recommend a repair rather than replacing the unit when the capacitor is the problem.
A central AC system consists of indoor and outdoor units. An indoor air handler can continue running when the outside unit has shut down. While air will blow from the vents, it won't be cooled; it may be as warm as the summer air outside.
The short answer: Definitely not. (Unless you have manually engaged your outside fan to run constantly, but it shouldn't be running for hours on it's own.) If your HVAC is functioning correctly, it should keep your house cool by cycling on for 15-20 minutes at a time—with distinct pauses in between each cycle.
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.
Water cooled systems (air conditioning without an outside unit) are plumbed directly into your water supply. They use the cold water in a controlled manner to cool the air through the piping system. Unlike traditional air conditioning systems, water cooled units do not require an outdoor unit.
Make sure the outside unit is turned on (there's probably a switch near the unit). If the outside unit has a separate circuit breaker, check your circuit box and make sure it hasn't been tripped. A more serious issue if the outside air conditioning unit's not working is a broken compressor, capacitor or fan.
If you think your air conditioner has blown a fuse, the first sign you'll notice is that the outside AC unit is inoperable. The best way to check for a blown fuse is by using a voltmeter. Be warned — you are working with live electricity and should use extreme caution when troubleshooting your system.
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.
Can You Replace an AC Capacitor Yourself? Replacing a capacitor is a relatively simple task that most people can do themselves with a little bit of research. However, it is important to remember that capacitors store a lot of energy, so it is necessary to discharge the capacitor before working on it.
Can My Air Conditioner Run on a Bad Capacitor? Over time, the capacitor can become corroded or damaged, which can prevent it from working properly. While your HVAC system may still run, it's not wise to continue using the cooling cycle until an AC capacitor replacement is installed.
On average, an AC capacitor might last between 5-20 years. However, some factors can affect the lifespan of your AC capacitor. For example, living in an area with high humidity levels like Florida can cause your capacitor to rust and break down more quickly.
Over time, the fan motor on the outside AC unit can wear out, causing the outdoor unit to stop working even when the inside AC unit is on. The fan motor can last 10 to 20 years with proper maintenance, like annual inspections and regular AC unit cleanings, but it will wear down faster without regular maintenance.
A tripped circuit breaker can be a major cause of why an outside AC unit isn't turning on. This occurs when the current is too high in the outdoor unit, causing the breaker in the fuse box or main electrical panel to switch off power to the unit, resulting in it not receiving any electricity.
Some air conditioning systems have a reset switch, which is a small, red button. Typically, the button will be on the outdoor unit. If you have a problem locating it on the outdoor unit, you may find relevant details on the equipment's manufacturer's manual. Press the red button for three seconds and release.
The simplest reason the AC unit isn't turning on is that the thermostat may be switched off or the circuit breaker may have a blown fuse. Alternatively, the unit's capacitor may be failing or there could be an issue with the condensate drain line. Finally, the unit might be low on coolant and need to be topped up.
The outside portion of your air conditioner is most often referred to as the “condenser unit.” Whereas the inside part of your air conditioner is responsible for absorbing heat from your home's air, your outside unit's job is to release that heat to the air outside.