What are the reasons for your AC freezing up?

Your air conditioner gives cool air by working under certain temperatures, airflow, and pressure. If any of these criteria go wrong or start acting out of balance, the refrigerant system of your AC can become too cold and start freezing up. Now, freezing up the refrigerant system of your AC or freezing up your system doesn’t mean that you will get colder air. In fact, it can have the opposite effect and start giving warm air. If not fixed on time, it can even lead to serious damage to your air conditioner. There are various reasons for your AC freezing up and we are going to discuss them in detail.

Reasons for your AC freezing up

Image credit: flickr.com

Let us explore the following reasons for your AC freezing up:

  1. Lack of airflow:

    The most common reason for your AC freezing up is the lack of airflow to the system. When the warm air can not flow over the coils when the compressor is running, the humidity will settle on the evaporator coils, causing your air conditioner to freeze up. Many situations can lead to a lack of airflow, and the following are some common ones: 
    a) Collapsed duct- Air moves through your home with the help of air ducts and if the ducts are blocked with something or if they collapse/fall apart, the airflow to the coils will be blocked. In such a case, even if the rest of your air conditioner is working properly, the evaporator coils will start freezing up due to a lack of warm air to maintain the required temperature. The duct or ducts of your house can collapse or be blocked because of many reasons such as ducts being too old, animal or pest nesting inside the ducts, etc. 
    b) Bad blower motor- The blower fan is responsible for blowing warm air over the evaporator coils and thus plays a vital role in the proper functioning of your air conditioner. But if the blower motor or the motor’s run capacitor or the blower fan is damaged in any way, the regular flow of warm air over the coils will be blocked.  This will ultimately lead to the freezing up of the coils. Signs that there is some issue with the blower motor or fan can be rattling or squealing sound from the blower, blower not turning on at all, and/or burnt wire smell coming from the unit.


    Image credit: pixabay.com

    c) Low voltage to the fan- The lack of airflow can also be caused due to the low voltage to the blower fan or motor when the compressor is running. The fan or motor running under-powered will lead to your air conditioner freezing up. 
    d) Clogged air filter- The air conditioner filter stops the dirt and debris from entering the system, keeping them away from the coils and compressor, and it also helps in a proper airflow to the system. But when a filter gets dirty, it starts blocking the airflow to the coils instead of ensuring it. Slow or blocked airflow due to clogged filters result in frozen evaporator coils, and a freezing system. 

  2. Dust blocking evaporator coils:

    Dirt can get to coils if the filter of your air conditioner is dirty or of low quality. Also, if you run your AC without a filter, dirt and debris will stick to the coils, making it hard for them to work properly. The surface of the refrigerant line is often damp due to the moist air condensing on it. When dust and other particulate reach the coils, they form a thick layer on them, trapping the cold inside the coils. When it happens for a long time, the coils become cold. Now, the excessive cold combines with the moisture on the surface of the coils and starts freezing the coils from outside as well.
    Image credit: pixy.org

    The top recommended filters for your air conditioner are:
    1. Air Purifier Whole House Uv Light in Duct for Hvac Ac (Air Conditioning) Duct Germicidal Filter + 2 replacement bulbs
    2. Original PURE AIR UV AIR Purifier Whole House Dual UV UVC Light in Duct for HVAC AC Duct GERMICIDAL Filter
    3. Trophy Air 20x25x1Pleated Electrostatic Air Filter Replacement | Washable | 6 Stage HVAC | Micro Allergen Defense, Healthier Home Environment | AC Furnace Air Filter Replacement | Made in the USA
    4. Air-Care 16x20x1 Silver Electrostatic Washable A/C Furnace Air Filter – Limited, Never Buy Another Filter!! – Made In the USA
    5. Flanders PrecisionAire 10155.011212 12 by 12 by 1 Flat Panel EZ Air Filter
    6. Purolator/Indigo Fiberglass Filter 20x20x1 (12 Pack)
    7. AIRx Filters Allergy 16x25x1 Air Filter MERV 11 AC Furnace Pleated Air Filter Replacement Box of 6, Made in the USA
    8. Aerostar Allergen & Pet Dander 16 3/8×21 1/2×1 MERV 11 Pleated Air Filter, Made in the USA, (Actual Size: 16 3/8″x21 1/2″x3/4″), 6-Pack
    9. Aerostar Home Max 20x20x1 MERV 13 Pleated Air Filter, Made in the USA, Captures Virus Particles, 6-Pack

  3. Low refrigerant:

    When there is a low level of refrigerant in your system, the conversion of the refrigerant from liquid to gas takes place earlier than normal because of the lack of pressure. This conversion creates an amount of cold that condenses the moisture on the coils and instantly freezes it. When the AC is run on low refrigerant for a long time, there is more ice build-up and it starts covering the copper pipes of your system. It will damage the entire air conditioner if not fixed on time. 

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How to fix this issue?

When you notice ice build-up around or near any part of your AC or when your AC starts giving warm air, you should turn off your thermostat as a first step to fixing it. Turning off the compressor will stop the refrigerant from getting colder. You should also check your air filter, if it is dirty or damaged and clean or replace it. Then immediately contact an air conditioner expert for repair. If you keep running your air conditioner even after noticing the ice build-up or after noticing any of the issues mentioned above, your air conditioner can end up permanently and seriously damaged. The issue of your AC freezing up can be fixed, but you have to act on time and take help from professionals, to be on the safe side.

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