Stay Cool: 5 Tips for Troubleshooting Frozen Evaporator Coils

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air conditioner with techStaying frosty can be hard to do if your A/C conditioner’s evaporator coils are doing the same. Frozen coils can stop your air conditioning system dead in its tracks, preventing it from delivering the cool, conditioned air you expect from your system. The following offers a few crucial tips for troubleshooting frozen evaporator coils.

Understand the Potential Causes of the Freeze-Up

When the evaporator coil absorbs the latent heat found in the surrounding air, it also reduces the air’s ability to hold large quantities of moisture in vapor form. As the air cools, the vapor condenses into a liquid, which falls on the coil and later drips into a catch pan underneath the coil.

Since condensate regularly comes into contact with the evaporator coil, and the coil’s own external temperature hovers just above freezing, there’s always a possibility for frost to form on the coil’s surface. The problem starts when sheets of ice begin to accumulate on the coil. Over time, the coil will eventually be encased in ice, preventing the refrigerant within the coil from absorbing latent heat and causing the unit to lose its cooling effectiveness.

Airflow blockages can also lead to frozen evaporator coils. Without enough air flowing through the coils, the refrigerant pressure eventually drops and the coils begin to ice over.

Give the Frozen Evaporator Coils Time to Thaw

For your first step, turn the air conditioning system off and give the frozen evaporator coils a chance to thaw out. You can do this by shutting the unit off at the circuit breaker. Left to its own devices, it could take up to 24 hours for the coils to thaw completely.

You can speed this process up somewhat with the help of a hair dryer, especially if you need your A/C unit up and running as soon as possible. Be careful not to overheat any portion of the evaporator coil or the lines running to and from it.

For cases of moderate frost, you can leave your HVAC unit on and set it to "fan only." This allows air from the blower fan to melt away the frost without shutting the unit down.

Check the Airflow

The next step involves checking the A/C system for adequate airflow. The air filters are most likely to be clogged with dust and debris, thus preventing air from flowing through unimpeded. Simply replace the air filter and vacuum the surrounding intake housing for good measure.

Make sure the evaporator coil itself is free of dust and debris. If you spot any debris or see algae and mold growing on the coil’s surface, don’t hesitate to clean the coils. Keep in mind that it’s easy to damage the aluminum fins lining the evaporator coil, so this may be a job better suited for your HVAC technician.

Inspect for Physical Damage

Check the evaporator coil for any signs of physical damage. Bent coil fins, dented pipes and damaged fittings could lead to icing problems. Any and all damage should be repaired by your HVAC technician before using your air conditioning system again.

Check Refrigerant Levels

Low refrigerant levels can create a low pressure environment within the refrigerant lines, making the evaporator coil’s external temperature fall below freezing. This, in turn, allows the condensate on the coil to frost over. Low refrigerant levels are normally caused by a leak somewhere within the A/C system, usually at a fitting, faulty valve or even a pinhole leak in the evaporator coil itself.

Your HVAC technician is best equipped to deal with your air conditioner’s refrigerant issues, since measuring and recharging refrigerant is often a dangerous task that requires special tools and know-how.

If you want to learn more about dealing with frozen evaporator coils, check out the latest in A/C service from the pros at McWilliams & Son Heating & Air, or homeowners in Lufkin, Nacogdoches and surrounding areas can give us a call today at 936-465-9191 to schedule an appointment.