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HomeRepair HelpMars Central A/C RepairMars Central air conditioner coil icing up Repair
Mars Central air conditioner coil icing up
If your Mars central air conditioner has an evaporator coil frozen or you notice the AC coil freezing up, start by checking the humidifier damper. An open damper can let air bypass the evaporator coil, reducing airflow and causing the air conditioner to freeze up. Next, inspect the blower motor in the furnace or air handler. A failed motor or seized bearings can stop the blower wheel from circulating air, leading to AC icing over. A clogged blower wheel and housing can restrict airflow as well, so carefully clean dust and debris with compressed air or a soft-bristle brush. If the blower still will not run, a failed run capacitor or capacitor may be preventing the motor from starting. A defective thermal expansion valve, or TXV, can also allow too much or too little refrigerant into the evaporator coil and cause freezing. Turn off power before inspecting electrical components, and remember that capacitors and other parts may involve dangerous voltage. Refrigerant diagnosis or any repair inside the sealed system requires EPA 608 certification and should be handled by a licensed HVAC technician. Enter your Mars model number to find the exact replacement blower motor, blower wheel, 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 - Mars 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 - Mars 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 - Mars 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 - Mars 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 - Mars 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 Mars central air conditioner not cooling and the evaporator coil icing up?
What should I check if the AC blower motor is not running?
Can a bad run capacitor cause an AC coil to freeze up?
Is a defective TXV or low refrigerant causing my central air conditioner to freeze?
How do I find the correct Mars central air conditioner blower motor or capacitor?
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