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Why is my air conditioner not shutting off? It is natural for homeowners to worry about wasting energy. If your air conditioner isn’t shutting off, numerous malfunctioning components can be responsible for the problem, including:

  • Clogged air filters
  • Frozen evaporator coils
  • Dirty condenser coils
  • Fan or fan motor problems
  • Bad electrical relay switches
  • Failing thermostats 

Furnace Repair Toronto is a trusted partner in the Greater Toronto Area to handle all types of AC repairs and maintenance. Contact us today to get an appointment to schedule an emergency cooling repair! Here is what our experts have to say about why your air conditioning unit doesn’t shut off as it should do and how you can correct the issue.

Related: Why is my AC not cooling the house?

Is It Okay For Your Air Conditioner To Run All Day?

No. Even in scorching weather conditions, your AC shouldn’t keep running all day long. At least 2-3 cooling cycles should occur per hour, and each cycle should last for around 15-20 minutes. The unit will power down once the thermostat detects the set temperature and end the cooling cycle. 

When you notice your AC running all day long, you should pay close attention to the problem. You are not only wasting electrical power, but the unit will also sustain excessive wear and tear over time. Essential components of the system will start to malfunction, and you may have to replace them or the entire system before long. 

Check out this video that explains possible reasons for an air conditioner that does not shut off after reaching the set temperature.

Why Isn’t My Air Conditioner Shutting Off?

Here are some significant problems that could lead to your AC running without shutting off.

Electrical Issues

There are many electrical components in an AC system. A stuck relay switch will close the electrical circuit and end power to the air conditioner. The compressor contactor may fuse closed and let the condenser unit run continuously. If you cannot repair it yourself, you may need a technician to replace the problematic relay switch.

Faulty Thermostat

Replace the thermostat of an AC unit every ten years for your AC to work correctly. The thermostat sensors will gather dirt and prevent them from reading the correct room temperature. On the other hand, the electrical wiring of the thermostat can loosen and fray over time. It will disrupt the communication between the AC and the thermostat. 

Wrong Thermostat Settings

Your AC may constantly run if you set the thermostat temperature incorrectly. If the setpoint is adjusted lower than usual – which happens when multiple householders make thermostat adjustments – the unit will have to keep running to achieve the correct temperature though you may expect the AC to turn off sooner.

Faulty Fan Limit Switch

The fan motor may continue running even when the correct fan settings are selected. Continuous running may happen even when the AC isn’t cycling. The fan will continue to run when the fan switch sticks in the override position. You can reset the limit switch near the blower fan to stop it from blowing unless directed by the system’s thermostat. 

Dirty Condenser Or Condenser Coils

The AC begins the cooling process when hot air passes via the indoor evaporator coil. It cools the air while a dehumidifier removes excess moisture from the air. The system’s refrigerant will travel through the lines to the outdoor unit. The compressor will then pressurize the refrigerant before moving into the condenser coil to release heat.

When debris and dust accumulate on the condenser coils, the coil’s capacity to release heat from refrigerants is limited. The AC’s cooling power reduces when the condenser coils are dirty or dusty. When this happens, the unit has to keep running to cool each room in your home.

The outdoor condenser unit won’t have enough air movement to release heat into the atmosphere when debris blocks the outdoor condenser unit. Bits of mulch, grass clippings, tall weeds, and other debris dirty up the condenser’s fins and clog it. It prevents air from flowing, and the system will continue to operate all day long as it tries to generate enough comfort for your home.

Frozen Evaporator Coils

If your AC unit is operating, but the vents blow hot air, the reason might be frozen evaporator coils within the air handler unit or indoor furnace. Numerous system problems prevent the coils from getting enough heat. When this happens, the condensation of air during the cooling process freezes on the coil’s surface. When there is a layer of ice on the evaporator coils, it prevents the refrigerant from absorbing the heat in the air. Could cause water leaks as well.

Excess dirt buildup on the coil can result in frozen evaporator coils over time. Other reasons include a lack of airflow due to dirty air filters, low refrigerant levels, and blocked room vents. The evaporator coils can develop a heavy layer of ice when the condenser drip pan and the drain line are clogged. It leads to holding moisture within the system.

Dirty Air Filter

Dirty air filters will prevent air movement through the AC system. It may lead to several issues resulting in the AC running continuously. When the air filter gathers pollutants over time, the AC has to keep cycling to provide the necessary comfort in your home or office. 

Low Refrigerant Levels

Air conditioners have specific refrigerants to maintain a comfortable indoor temperature during the hot season. When there are leaks in the refrigerant lines, faulty components of the system will let the refrigerant escape. When there are low refrigerant levels, the system can’t absorb and transfer heat properly. The unit will run all day long to make up for this shortcoming. 

Low Fan Speed

The AC cannot circulate enough cool air into your home when the blower fan speed is too low. When this happens, your air conditioner will continue to work overtime as it attempts to circulate cool air into your living space. Dirt and grime accumulated in the fan blades can slow them down and restrict operations.  

Incorrect System Size

The correct fit is crucial when choosing an AC for your home since ACs come in different sizes. When you install a unit that’s too small or undersized, it won’t have enough power to cool your home. Then the system will have to run for hours to maintain a comfortable temperature in your home. The system will continuously run until you replace the entire unit.

What To Do When Your Air Conditioner Not Shutting Off?

There are a few troubleshooting steps that you could try before calling a professional to repair the unit when your AC keeps running without shutting off.

1. Adjust Thermostat Temperature Settings

First, check the set temperatures on the thermostat of the unit. If the set temperature is lower than the current temperature in the room, the AC will cycle continuously. Adjust the AC temperature a few degrees higher than your room temperature. The higher setting may trigger the thermostat to shut down the unit without running constantly.

2. Adjust Thermostat Fan Settings

Check the fan setting on the thermostat of the unit. The toggle should ideally be in the AUTO position to let the fan run while the AC is on. If your thermostat fan setting is ON – change it to AUTO. Now the thermostat should tell the fan to shut off. 

3. Eliminate Air Flow Restrictions

If there are obstacles to the air flowing freely through the system, you should remove them. Replace a dirty air filter with a clean one, clean the dirt and debris accumulated on the outdoor condenser unit, and open all the room supply vents in your home to eliminate airflow restrictions.  

4. Clean The Blower Fan

If the system has a dirty blower fan, it cannot circulate cool air properly. It causes the unit to run all day long to cool your home.

Follow these steps to remove grime that is limiting fan operation:

  • Turn off electrical power to the unit.
  • Remove the access panel of the blower compartment.
  • Unscrew the circuit board screws and move the circuit board out of the way to keep the wires connected.
  • Slide the blower motor assembly out of the cabinet by removing the screws.
  • Clean the debris on the fan blades using a soft brush, and vacuum dirt from the blades and cabinet.
  • Reposition the assembly in the cabinet and secure the screws. Screw the circuit board and access panel into place. Now restore power to the system.

Call Furnace Repair Toronto For All Of Your Air Conditioning Repair Services!

If your air conditioner is not shutting off, and you can’t fix the problem yourself, don’t hesitate to call us. Our NATE-certified HVAC experts will diagnose the issue and solve your problem immediately!

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