The AC unit freezes up for various reasons, such as a dirty or clogged return vent, obstacles in the ducts, or a malfunctioning blower motor. Other things that could cause your unit to freeze are a refrigerant leak, dirty evaporator coil, clogged condensate line, or drainpipe issue. There could also be problems with the condenser circuit board and outdoor air metering device.

Consult us when you’re unsure about what’s happening with your AC unit. At Dring Air Conditioning & Heating, we have a highly skilled team of professionals that can inspect and handle any HVAC issues. Here is a step-by-step guide about what to do when your AC unit freezes up.

1. Turn the AC Off and Switch the Fan From Auto Mode to On

If your AC unit starts freezing up, shut it off immediately. You can either turn off the thermostat or circuit breaker. Turn on the blower, and let the fan run as long as it dries out and defrosts. It may take more than a day to defrost. Wait for the AC system to dry before turning the AC on again. Use this time to identify the underlying issues. The following steps will help you identify the cause.

2. Inspect the Motor and Test the Efficiency of the Blower

The fan must work efficiently all through the defrost cycle. The air that enters the return inlet should be evenly distributed over the AC unit. A failing blower or motor may cause uneven airflow. Engage an HVAC specialist to fix the issue and to get your AC back up and running. An AC unit needs constant air supply for efficient cooling and optimum functionality.

Your AC may freeze up if the humidity-control evaporator coil is not working. If the blower motor is faulty, you need to replace it. If not, it needs to be checked. The control board may be defective if there is no power in the blower motor. In addition, insufficient lubrication on the motor and fan may lead to further damage. HVAC maintenance routines can prevent such problems. Contact Dring Air Conditioning & Heating for the best HVAC maintenance services.

3. Clean Up or Replace the Return Air Filters and Others

If the test shows that the blower and motor are functioning optimally, check all the air filters throughout the HVAC system. Start by examining the return air filter. If it is clogged, replace it with a new one. The air from your AC unit needs to circulate properly and freely. Keep the filter clean, and don’t cover any vent on your AC unit. Besides, the evaporator coil will not absorb heat from the outside if it does not have refrigerant. As a result, your AC unit will freeze up.

4. Open the Dampers and Supply Vents

Next, you must confirm that the supply ducts’ dampers are open. When inspecting the air filters, confirm whether the supply vents are either wholly or partially closed. Lastly, check for clogged or blocked vents in less-used rooms.

5. Clean Up the Ducts and Remove Any Obstructions From the Vents

Ducts and vents must always be open without any obstruction from hair, clothing, flooring, or debris. It’s always advisable to check whether the return vents have been blocked by fabrics or furniture placed in front of them. This might block the airflow into the HVAC unit. It is common for dust and debris to accumulate inside the ducts and vents. Put a lot of effort into cleaning your home’s vents and ducts to ensure sufficient airflow. Dust and debris buildup can reduce airflow leading to inefficient AC units.

6. Inspect and Unclog the Condensate Line and Drain

The condensate line connecting the AC unit to the drainpipe must be open without obstruction or blockage. Otherwise, the debris buildup and water will accumulate in the reservoir attached to your AC unit. As a result, more moisture will gradually condense on the coils and eventually freeze. Check the condensate line if your AC is frozen to find where it leads. Follow the line and drain to the outside of your house, where you will see constant water dripping.

If there is no dripping water from the drainpipe, the condensate line is likely clogged, leading to frosting. Most modern HVAC units use a pump in the condensate reservoir to control the water levels. If the pipes are not blocked, the pump might be faulty. Besides, you might have some water pooling on your garage or basement floor during the defrost process. Old sheets and rugs can be used to contain the mess and slowly soak up any water.

7. Inspect and Clean Up the Evaporator Coil

Look in your indoor AC unit’s evaporator chamber to check the location of the freezing problem. As the ice melts, you might see a dirty evaporator coil. It’s also common for evaporator chambers to rust and get moldy, resulting in blockage. Older AC units usually have rusty evaporator chambers, but coils may also corrode if they freeze repeatedly.

Any abnormal rust buildup may indicate leaking refrigerant or evaporator coil. Always ensure your evaporator coils are thoroughly cleaned by Dring Air Conditioning & Heating after it defrosts and dries up. Our experts are certified with vast experience in all HVAC-related issues. The damaged or malfunctioning HVAC components must be inspected, repaired, and fully revamped for improved performance.

8. Contact a Certified HVAC Technician to Check and Fix Refrigerant Leakage

Low refrigerant levels are among the major reasons your AC would freeze up. If the refrigerant is low, never attempt to refill it all by yourself. You should also check for any leaks that may affect normal temperature control. Be aware that refrigerant leaks should only be fixed by specialists. Besides, there may be other underlying issues behind the freezing problems, such as a malfunctioning or blocked metering device in the coil. You may have electrical issues due to:

  • Failing circuit board
  • Failing expansion valve outside
  • Broken capacitor
  • Compressor or condenser issue

Some complex problems require taking apart your outdoor or indoor units for a thorough inspection. Undersized return ducts or oversized AC can make the indoor unit freeze up due to inadequate airflow in the system or an excessively cold evaporator coil. These issues can affect your HVAC system and cause condensation. This can be a primary concern for some building managers and owners because the effect on such a large system can be catastrophic and expensive. That is why you should call for a professional opinion at the first sign of an issue.

Why Choose Us

Dring Air Conditioning & Heating offers the best HVAC services in Carrollton and the DFW Metroplex. Our ultimate goal is to keep your home comfortable throughout the year. Our services include AC repair and installation and heating repair and installation. Other services include indoor air quality, air duct installation, thermostat, and fan coils. We also offer indoor air quality products and testing to ensure you breathe clean air. Lastly, we are available 24/7 for emergency services, including heating, cooling, and IAQ.

Call Dring Air Conditioning & Heating now for more information!

Dennis Chaisson

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