My Air Conditioner Fan Keeps Running When Turned Off

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Updated September 16, 2022

If your air conditioner keeps running when turned off, you may have a severe problem leading to higher energy costs on your energy bill. Even the best air conditioners experience issues occasionally, and routine maintenance and repairs should be scheduled for extensive problems.

KEY TAKEAWAYS:

  • One of the common reasons is that you may have a faulty broken thermostat if your AC runs while the thermostat setting is turned off, especially if your house seems colder than your desired temperature.
  • Faulty wiring and a stuck relay switch may cause electrical issues.
  • Call a repair specialist if your contactor is fused in a closed position.

If your AC won’t turn off, even if the thermostat switch reads off and the current room temperature still feels the same after some time passes, you may have electrical issues, an old or faulty thermostat, or problems with your contractor. Once you’ve identified the problem, you can either schedule a repair or do it yourself, though there are some repairs that only certified technicians should handle. For example, ‌pay attention to whether your air conditioner makes a loud noise when it shuts off, or if the air conditioner is running when the heat is on. These will likely require a repair specialist.

Why Does My AC Keep Running When It’s Off?

Your air conditioner may continuously run despite being turned off for several reasons that you can usually fix with regular maintenance, including replacing a dirty air filter and cleaning a dirty evaporator coil or condenser. However, only a professional should handle electrical issues, faulty thermostats, and contactor issues. But for installing a quiet through-the-wall A/C? That’s something you can do with the right instruction guide.

Insider Tip

If your room feels colder than your desired temperature, you may have a blocked or dirty sensor on your thermostat.

You should not try to fix any wiring problems yourself unless trained to do so. Similarly, if your compressor contactor is stuck in the closed position, your system already has a steady power supply, which could shock you if not handled properly. You may also be interested in learning why your air conditioner heater is not working.

Faulty Thermostat

A faulty thermostat is one common problem that causes air conditioning units to run while switched off. Thermostats allow you to set your preferred temperature, mode, and fan behavior. In addition, they have temperature sensors that read the room’s temperature and determine when to stop the air conditioning system.

Thermostats often malfunction due to age, especially if over ten years old. Age increases the chance that these crucial devices may not work as they should. In this case, consider replacing your thermostat with a new model.

Dust can also cause issues as it collects on the temperature sensor, providing an inaccurate reading. You may notice the ambient temperature in your home feels lower than the temperature to which you set it. This issue may also turn the AC off by itself.

Electrical issues

A few different electrical issues may occur throughout your AC’s lifespan. For example, you may have a stuck relay switch or bad wiring.

The relay switch controls the circuit that provides power to the system. When it gets stuck, it causes the circuit to stay closed. In other words, the air conditioning system has a steady and constant flow of power, which can drive up energy costs and cause the system to run more often.

Meanwhile, wires control the system and transport power to your unit. If your wires were installed incorrectly or they have loose connections, the unit might run longer than anticipated. Wires also suffer from wear and tear like other components, so they may be damaged and need work as well.

Contactor Issues

AC units sometimes have trouble with the compressor contactor that controls the power flow to your machine’s condenser. However, this switch may freeze into a permanently closed position.

If this is the case, the system will experience a similar effect as that produced by a stuck relay switch since the contactor allows a constant flow of power. This excess energy causes the air conditioner to run longer than necessary. This is one issue that you’ll need to contact a technician to fix.

Warning

Attempting AC repairs on your own is dangerous, so you should call for a professional service provider for most problems.

F.A.Q.S

Is it normal for my AC to run all day?

Your AC should not be running all day, so you may need to schedule a regular maintenance or repair appointment with a technician.


Why won’t your HVAC fan turn off?

The thermostat controls the HVAC fan, meaning a faulty thermostat may cause your fan to run for more extended periods than necessary. If your relay switch or contactor is stuck, your AC is getting a steady electricity supply instead of only getting electricity when needed so that it won’t turn off.


Why is air running when the thermostat is off?

You may have bad wiring if your thermostat is set to OFF and none of the other issues seem to fit your situation. You should also double-check your settings.


STAT: Faulty relays, bad wiring, or a faulty thermostat can cause the A/C fan to run constantly. (source)

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