Common Reasons Why Your Air Conditioner Freezes Up

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Why do you need regular air conditioner maintenance?

As summer is fast approaching in Southern California and you are using your air conditioner more and more often, it may come as a surprise to see ice particles, or even blocks of ice, form inside or outside your unit. 

Air conditioners are designed to cool the inside of your house, but why do the outside parts of your unit look like the insides of an old freezer? 

Even if you spend 90% of your day inside your home, you ignore cleaning your air conditioner. When was the last time you had your air conditioner serviced, cleaned, and inspected? 

The problem of your air conditioner freezing up usually arises due to the lack of regular air conditioner maintenance. 

Avoid Higher Replacement Cost by Scheduling Regular Air Conditioner Maintenance 

If left unchecked, air conditioners that freeze up will eventually stop working, which will lead to higher expenses of replacement. 

Before matters get out of hand, call the experts at Home Comfort USA for a 32-Point Tune-Up and let our expert HVAC technicians check for faulty parts, replace your filter, and give your unit the cleaning it deserves.

Why Does Your Air Conditioner Freeze Up?

An air conditioner can freeze up if you don’t clean it regularly, has a leak that you need to repair and refilled, or if you’ve set the thermostat too low. 

Blocked airflow

Unrestricted airflow is necessary for your air conditioner to function properly. it restricts the exchange of thermal energy between the HVAC system and the room. This leads to a drop in the temperature of the cool air trapped in the evaporator coil. As a result, ice gradually forms around the evaporator coil and fins.   

  1. air filterDirty air filters

If you have recently been doing woodcutting, construction, painting or wall sanding, your filter will suck in the fine dust. 

When you have a dirty filter, the evaporator coil won’t have enough airflow and slowly it will build up ice. The longer you operate your unit, the more it will freeze. The refrigerant lines that go outside will freeze up as well. 

To prevent blocked airflow, remove air filters at least once a month and wash them with water and soap. 

Air filters trap dust and other contaminants from entering the evaporator fins so cleaning them regularly is highly recommended. Dirty air filters not only lead to air conditioner clogging and freezing but also contribute to poor indoor air quality.  

  1. Clogged evaporator coil and fins

Dirty air filters can also clog up the evaporator coil and fins. If you do not know how to clean them using a spray-type cleaner, ask your HVAC technician to remove the entire evaporator for cleaning. Schedule regular maintenance of the evaporator coil and air filters to ensure that your unit does not freeze and continues to function properly.

  1. Blocked vents and return grill

You may not notice but as you move furniture around, you may have inadvertently put a couch or a cabinet in front of a return grill. This has the same effect as having a plugged filter. 

If your air conditioner is freezing up, try opening all your vents and return grills. Never tape off a return grill with cardboard or paper.

  1. Blocked metering device

Moisture, debris, dirt, or other smaller contaminants may be trapped as refrigerant is spinning around that can plug up the metering device. If something is blocking the metering device and the refrigerant is having a hard time going through it, there will be lower pressure inside the evaporator coil. 

Lower pressures equal lower temperatures so it will cause the condensation on your evaporator coils to freeze up. Unfortunately, this is not a DIY project so you will have to call an HVAC technician to figure this out. 

Low refrigerant 

A refrigerant leak leads to a low refrigerant in your air conditioner. If this happens, it will take a lower temperature for the compressed refrigerant to become vapor. The temperature of the cooling coils is now lower compared to its original design. This lower temperature turns moisture from the air to ice on the evaporator when the temperature goes below 32 °F.

Moisture stuck at the evaporator coil and fins continues to produce ice around them until it forms a block of ice.  

  • When you see the ice forming on the evaporator, turn off the unit and wait for the ice to melt.
  • Turn your fan setting in the thermostat from automatic to on and it will take a day or two depending on how much ice has built up to thaw the ice out.
  • Keep in mind that the ice will not always go neatly down into the drain pan. It will go down on the sides of your furnace so place some towels and expect a little puddle on your furnace as ice will thaw.
  • Immediately contact a professional HVAC technician. There are strict requirements for adding refrigerant and repairing refrigerant leaks.

Extremely low temperature and fan settings

Air conditioners are designed to cool most efficiently to the lowest temperature of 68 degrees. They can go colder but setting the temperature lower for a long period can cause the unit to freeze up. Do not set the temperature of your unit lower than 68 degrees. 

Do not run the fan on low while on low-temperature setting to prevent freezing the coils. Use a low fan setting only when the outside humidity is unusually high and the air conditioner is having difficulty keeping the room dry. 

Damaged blower fan

When the air conditioner is on, check that air is coming out of the unit. The blower fan helps get cold air to circulate inside the room and pushes the warm air outside. 

If you have a damaged blower fan, there comes a significant change in the airflow of your air conditioner. Excessive condensation will build up in the coils and the water droplets will not properly drain or evaporate. 

If the blower fan does not make hot airflow through the right parts, the refrigerant line might freeze as well. The freezing can easily move up to the condenser outside, causing more serious problems. 

If the blower fan does not work, its fan motor may have burnt or loose connections. Contact an HVAC technician to check the reason of your unit’s blower fan malfunction and for immediate repair. 

Call the Comfort Guys of Southern California, We’re There

At Home Comfort USA, we fix all kinds of HVAC problems for residents and businesses, including air conditioner freeze-ups. We know that the summer heat in Southern California is sweltering and can be dangerous to your health so you can call us any time of the day and we will respond quickly for HVAC repair. Your indoor comfort is our highest priority. 

Call us at 888-462-0089 or schedule a maintenance check from Home Comfort USA today!

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