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HomeRepair HelpTrane Central A/C RepairTrane Central air conditioner coil icing up Repair
Trane Central air conditioner coil icing up
If your Trane central air conditioner has an evaporator coil frozen, ice forming on the coil or refrigerant line, or the AC icing over, restricted airflow is the most likely cause. First, check whether the humidifier damper is open instead of set to summer mode. Next, inspect the blower motor, which may have seized bearings or failed electrical continuity, then check the blower wheel and housing for dust and debris that can limit airflow. A defective run capacitor or blower capacitor can also prevent the blower motor from operating and cause an air conditioner freezing up. Less commonly, a faulty thermal expansion valve (TXV) can mismanage refrigerant flow and create a frozen AC unit. Cleaning the blower wheel and checking the damper are reasonable DIY steps, but disconnect power before servicing. Testing capacitors, blower motors, and other components may involve dangerous 240V line voltage, so use proper safety procedures or hire a qualified technician. TXV diagnosis and any refrigerant or sealed-system repair require an EPA 608-certified, licensed HVAC technician. Enter your Trane model number to find the exact replacement blower motor, blower wheel, run capacitor, capacitor, or TXV for your central air conditioner.
01 - Humidifier Damper is Open
An open humidifier damper will let air bypass the evaporator coil. This loss of air flow can cause the evaporator coil to freeze up. If you have a humidifier on your furnace or air handler, confirm the humidifer damper is in the "summer mode" or closed position.
Highly Likely
02 - Trane Central Air Conditioner Blower Motor
Since the furnace or air handler blower motor is the component that circulates the air through unit to cool it, a defective blower motor could result in the evaporator coil icing up. You can use a multimeter to test the blower motor for electrical continuity, a continuous electrical path present in the motor, as well as determine if power is reaching the motor. You can also try turning the blower wheel by hand. If the wheel does not turn freely, it's likely the motor bearings have seized and the blower motor will need to be replaced.
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Highly Likely
03 - Trane Central Air Conditioner Blower Wheel and Housing
Over time the blower wheel and housing can become clogged with dust and debris. This will restrict the air flow which could result in the evaporator coil icing up. You can try cleaning the blower wheel with compressed air or with a soft bristle brush. Use caution when trying to clean the blower wheel as the fins are sharp and can be easily damaged. If the blower is damaged it will need to be replaced.
Common
04 - Trane Central Air Conditioner Run Capacitor
If the run capacitor is defective, the blower fan motor may fail to run which could result in the evaporator coil icing up. To determine if the run capacitor has failed, test the capacitor with a multimeter. If the capacitor is unable to hold and release a charge or is bulging or leaking, replace it.
Common
05 - Trane Central Air Conditioner Capacitor
If the capacitor is defective, the blower fan motor may fail to run which could result in the evaporator coil icing up. To determine if the capacitor has failed, test the capacitor with a multimeter. If the capacitor is unable to hold and release a charge or is bulging or leaking, replace it.
Common
06 - Trane Central Air Conditioner Thermal Expansion Valve
A thermal expansion valve, commonly referred to as a TXV, regulates the amount of refrigerant in the evaporator coil to help maintain an optimal working temperature.
Common
Frequently Asked Questions
Why is my Trane air conditioner coil freezing up?
Can a blower motor or dirty blower wheel cause an AC coil to freeze?
Can a bad run capacitor cause my air conditioner to freeze up?
What should I do if my AC coil keeps freezing after cleaning the blower?
How do I find the correct Trane air conditioner replacement part?
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