Why Does My AC Keep Turning On And Off? 10 Causes & Solutions

Liz Yang

Picture this: after a long day of hard work, you return home, turn on your air conditioner, and then lie on your sofa, trying to get some rest. However, your air conditioner keeps turning on and off, rendering it incapable of cooling the room. How frustrated will you be?

This phenomenon is commonly referred to as short cycling, and it is a common problem with air conditioners.

In fact, there is an array of reasons that can lead to an ac turning on and off repeatedly, and the solutions are different. Feel daunting? Don’t worry! I have summarized all the causes and solutions in this post.

Let’s get started!

1. Malfunctioning thermostat

damaged thermostat

The thermostat is an important component of an air conditioning system because it controls when the system turns on and off, as well as which mode it should operate in.

Normally, it includes a sensor that detects the ambient temperature. When it fails, for example, because the wiring is loose, it can send the incorrect signal to the ac, causing it to turn on or off at the wrong time.

It’s also possible that the thermostat’s battery is running low, preventing it from working properly. When the thermostat is turned off, the air conditioner will turn off as well.

What to do?

If you notice the display is blank, replacing the batteries will most likely solve the problem. Otherwise, you should hire a certified HVAC technician to repair it.

2. Wrong thermostat placement

Again, the thermostat makes decisions based on a sensor. That is, if the air around the thermostat does not represent the true ambient temperature or if the airflow is not stable, the thermostat will continuously stop and start the air conditioner.

For example, if the thermostat is near the air vent from which the cool air is emitted, it will turn off soon after the ac is turned on because the surrounding air is cold. When the ac is turned off, the ambient temperature rises rapidly, causing the ac to turn on again in a few minutes.

What to do?

Place the thermostat on an interior wall away from air vents, direct sunlight, windows, and the kitchen.

3. Dirty air filter 

dirty ac air filter

Your air conditioning system requires a certain amount of air to function normally.

When the dirty filter becomes clogged, it restricts airflow, forcing the fan to work harder to get more air. The system then overheats and shuts down as a result of the protection mechanism. However, once the machine has cooled down, it will restart.

Some people complain that their air conditioner cycles on and off every 10 minutes, which could be due to a dirty filter.

What to do?

The air filter can be cleaned or replaced on your own. Unplug the power cord, remove the filter, rinse it under running water, and scrub the stubborn grime away with a brush. Once the air filter is dry, replace it.

4. Frozen evaporator coil

When the evaporator coil freezes, your air conditioner will experience short cycling. Models will now turn off automatically in this situation to allow the ice to thaw. Electrical components will not be harmed in this manner.

The machine will restart once the ice has melted. That is why it turns on and off automatically.

What to do?

A frozen evaporator coil can be caused by a clogged air filter, a refrigerant leak, or dirt and dust. You can clean the filter to see if the problem has been resolved. If not, you should seek professional help to identify and resolve the issue.

5. Refrigerant Leak

Refrigerant can leak out through the small holes in the coils due to tear and wear or other factors. It can cause the evaporator coil to ice up as well as lower the pressure in the compressor, causing the air conditioning unit to shut down.

After a while, the pressure will rise, and the machine will restart.

What to do?

R22 Freon was once used as a refrigerant in air conditioners, which can contribute to ozone depletion. Even though the R401 refrigerant used today is safer, it can still cause respiratory problems. As a result, you should hire a professional to check the refrigerant level, locate and repair the leak.

6. Dirty condenser coil

clean ac compressor coil

The condenser coil is essential for heat transfer. Because it is outside, it is prone to dust and dirt. If it is coated with these contaminants, heat can’t easily escape, causing your air conditioner to overheat and experience short cycling.

What to do?

You may be able to clean the condenser coil yourself, depending on the model. Before cleaning, make sure the machine is turned off.

You can remove debris with a brush and dissolve buildup on the fins with cleaner. Before reassembling the outside unit, rinse and dry the coil.

7. Broken compressor

When the compressor fails, it can easily overheat, causing your air conditioner to cycle on and off until it stops working completely.

It is possible that other components in the ac will be damaged during this process, so you should take action as soon as possible.

What to do?

The compressor may be the most expensive component of an air conditioner. If your air conditioner has served you well for several years, purchasing a new unit may be preferable. You can also hire a certified HVAC technician to replace or repair it.

8. Damaged capacitor

The capacitor is in charge of supplying constant power to the ac, ensuring that it can operate continuously. When it is damaged, your air conditioner cannot accept stable power and will begin to kick on and off every few minutes. 

What to do?

Because working with electrical components is hazardous. To diagnose the problem, you will require the assistance of a technician.

9. Oversized AC unit

The secondary effect of ac is to dehumidify the air. However, many people find that their houses are still humid even when the ac is on.

This is usually due to the ac being too large for the room. When the air conditioner is turned on, it quickly lowers the air temperature and then turns off automatically.

It does not have enough time to dry out the air. It will resume working when the temperature rises a few minutes later.

That’s why your air conditioner cycles on and off.

What to do?

You should have an HVAC company recalculate how large your ac should be for you and, if necessary, purchase a new machine.

10. Partially clogged drain line

Modern air conditioners include a float switch that can turn the machine off when the drain pan is full. Over time, more buildup can accumulate in the drain hose, obstructing water flow.

If your air conditioner produces too much water in a short period of time, the drain pan may fill up, and the machine will shut down because the drain hose cannot expel all of the water. However, the machine will restart after a few minutes because the water level in the drain pan will decrease if the drain line is not completely clogged.

What to do?

The problem can be solved by sucking or dislodging the slime in the hose with a brush or vacuum.

Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested a lot of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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