Here Are 6 Reasons Why Your AC Isn't Working

It’s getting to be that time of year when the outside temps are warming up, and you may be looking to your central air conditioner to keep inside temps under control. Sometimes, though, your AC doesn’t hold up its end of the bargain.

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If your central air conditioner stops suddenly or gradually struggles to keep your home cool, you could be dealing with a repair issue. Some problems are minor and can be fixed quickly. Others require an HVAC technician to do the repair safely.

When things get sweaty, doing some investigative work could help you figure out why your AC isn't working. Minor issues related to the power source, thermostat or filter are often simple to fix yourself. If one of the internal parts is damaged, you'll likely need a professional repair. The following issues can cause your central air conditioner to stop working.

1. Power Source Issues

If your AC doesn't turn on at all, you could be dealing with a power source issue. Start by checking the breaker switch or fuse that controls your HVAC unit. The AC could have tripped the breaker or blown a fuse, which is simple to correct. Your unit also typically has a disconnect switch inside and outside near the exterior unit. If one of these switches gets moved to the off position, the unit won't turn on. Check the switches to make sure they're turned on.

2. Malfunctioning Thermostat

Your thermostat could also be the root of the problem. If the thermostat screen is blank, you know it's likely the culprit. Some thermostats use batteries as a power source. Put in fresh batteries to see if that fixes the issue. If that doesn't help, there could be a thermostat wiring issue, or it could be completely dead and need to be replaced.

It's also a good idea to check your thermostat settings. Make sure it's set to the “cool” function. Check the temperature setting to ensure it's lower than the current room temperature. If your home is already cool, the AC won't turn on until it heats up past the temperature setting.

3. Dirty Filter

Changing your HVAC filter regularly is an important maintenance task. If you don't change or clean the filter, it can get clogged with dust, pet hair and other debris. A dirty filter prevents adequate airflow, which can make the system work harder. You might notice less air flowing through the vents, or the system might run more to keep up with your cooling needs. Dirty filters can cause the coils to freeze, which keeps the AC from producing cold air. You might also notice an increase in your utility bills due to the extra work the unit is doing. Changing or cleaning the filter should fix this issue. Check the filter monthly and change it at least once every three months to prevent these issues.

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4. Other Dirty Parts

Dirt can build up on other AC components, particularly the coils and the outdoor unit, which can prevent the system from running properly. Your air conditioner might still run, but you'll likely notice warm air instead of cold air coming out of your vents. It might never reach the temperature you set on the thermostat, despite running constantly. The coils can also ice over if they're dirty. This can contribute to warm air coming from the vents and could cause the system to shut down completely. You can take the cover off the indoor unit and look at the coils to see if they're frozen.

5. Refrigerant Leaks

Every air conditioner uses refrigerant to cool the air. Your system doesn't run low on refrigerant when it's working properly. However, it can develop leaks that cause a drop in the refrigerant level. Your system will still run, but it won't be able to cool the air properly. Refrigerant leaks can cause your coils to freeze. You might hear bubbling or hissing sounds or smell a sweet odor near the unit.

Refrigerant is a dangerous substance and shouldn't be handled by homeowners. If you suspect your air conditioner has a refrigerant leak, call an HVAC technician immediately to assess the situation.

6. Damaged Components

Your air conditioner has many critical interior parts that could go bad, including fan motors, capacitors and condensate pumps. You'll often hear strange noises when a component fails. For example, a bad capacitor can make a humming sound, but the unit won't start running. Other times, you get a visual sign. If the condensate pump goes bad, the unit might not turn on, and you could see water around your AC unit. A damaged blower fan might work intermittently or stop working altogether. If you've checked out the minor issues with no success, you could be dealing with a damaged part that a technician needs to fix.