Mini-split air conditioners cool indoor spaces by using the refrigeration cycle. A healthy unit cycles on and off a few times each hour. Once the home attains the pre-set thermostat temperature, the unit turns off and comes on again when the temperature rises. Therefore, if your mini-split is running non-stop throughout the day, it is defective. If your air conditioner is constantly running, check and repair the components below.

Faulty Thermostat Sensor

An air conditioner's refrigeration cycle relies on the thermostat. The thermostat uses sensors to detect the temperature of the indoor air. If the temperature is above the programmed setting, it signals the AC to turn on and cool down the indoor space. If the thermostat has a faulty sensor, it won't accurately detect the ambient temperature. Consequently, the AC will continue to cycle as the thermostat won't signal it to turn off. Therefore, replace the faulty thermostat to restore the unit's normal cycles.

Low Refrigerant in the System

Mini-split units use refrigerant to remove heat from the indoor air. The refrigerant cycles inside the condenser, where it absorbs heat from the indoor air. It then flows to the outdoor unit and releases the heat outdoors. If your AC is low on refrigerant due to leaks, there will be inefficient cooling. The unit will take longer to cool down the home, leading to longer or non-stop refrigeration cycles. If you hear hissing sounds near your indoor or outdoor unit, your AC is leaking refrigerant. Fix the damaged refrigerant line and recharge the unit to protect the system from failure. 

Frozen Evaporator Coils

Evaporator coils work with the refrigerant to absorb heat from the indoor air. The system must have adequate refrigerant for the coils to absorb heat efficiently. If the refrigerant levels are low, pressure drops inside the coils. This allows moisture in the air to accumulate and freeze on the coils. Frozen coils cannot absorb heat; thus, the condenser extends the cooling cycle to cool down the room. If you notice ice buildup and leaks around the coils, turn off the AC and recharge it.

Defective Blower Motor

The indoor unit has a blower motor that turns on the fan blades to blow cool air into the space. If the blower motor is defective, the fan may operate at slow speeds. The indoor air will take a long time to cool down, causing the AC to run non-stop. If the blower motor isn't working, your AC won't cool the space despite being on. Therefore, you must repair the defective motor to restore efficient cooling throughout your home.

If your mini-split air conditioner is running constantly for hours, check it for the above problems. Contact an AC repair contractor for troubleshooting and repair services.