Why Do Air Conditioners Freeze Up?
Picture this — it's a sweltering day in the middle of summer. You come home, plop down on the sofa, kick your feet up, and crank on your trusty air conditioner. About 10 minutes into relishing the cool air against your skin, your AC unit randomly quits.
A faulty air conditioning unit is the last thing anyone wants during a hot Canadian summer. But why is your air conditioning frozen? Learn more about what to do if your AC keeps freezing up.
What Causes Air Conditioners to Freeze?
A broken AC unit can quickly send temperatures skyrocketing in your home. However, since an air conditioner has so many moving parts, it can be difficult to pinpoint what's causing the issue. In most cases, calling a professional is the best way to diagnose and remedy the problem. Here are some common reasons an AC freezes up.
1. Poor Airflow
Weak airflow is one of the most common culprits of a frozen AC unit since airflow is critical in an air conditioning system. Various factors can cause low airflow, including a damaged motor blower, insufficient fan power, a clogged air filter or coil blockage.
Disrupted airflow between your home and AC unit reduces the essential exchange of thermal or heat energy. As a result, cool air concentrates around the condenser coil and evaporator fins.
The temperature surrounding these components drops, which can result in ice formation. If this continues, the entire unit will eventually freeze up. Inadequate air circulation means there isn't enough heat energy to condense the moisture.
To resolve this issue, you'll need to call an expert to check for ductwork leaks or blockages. They can improve your airflow and prevent ice development.
2. Low Refrigerant Levels
Refrigerant is the chemical in your air conditioner that generates a cooling effect while vaporizing or expanding. If your AC unit is low on refrigerant, it will have a lower saturation point and require more extreme temperatures to turn condensed liquid into vapor. That means coil temperatures are lower than they should be.
Due to the accumulated moisture from the air's heat and humidity, water vapor will freeze on the coil's surface, resulting in ice buildup. Rather than condensing into water and draining from the pan, the moisture builds up around the evaporator fins and coils.
Low refrigerant levels typically result from a leak somewhere in the system. A professional can inspect your unit, locate the leak and correct the problem so your AC can function normally.
3. Faulty Blower Fan
The blower motor and fan are responsible for blowing warm air to the coils, helping create cool air. Essentially, the fan releases cold air while bringing in warm air.
When air cools inside the system, it becomes denser and movement is reduced. Besides hindering warm airflow, a damaged fan can freeze the line holding the refrigerant, which can extend to the AC unit's external area. Insufficient airflow from a damaged blower fan can cause the coil to freeze up.
Your vents can't release cool air when this fan malfunctions, which can cause a frozen air conditioner. If your blower motor and fan are causing the issue, you might hear rattling coming from your AC unit. Sometimes, your fan may not receive enough power from your home's electrical system.
If you suspect an issue with your blower motor and fan, it's best to seek help from an expert since a damaged blower fan can compromise your entire heating and cooling system. A professional can inspect your blower motor and fan and take the proper steps to restore your AC unit's function.
4. Obstructed Drain Line
If your central air keeps freezing up, a drainage-related issue could be the problem. In addition to cooling air, your AC system also removes humidity to maintain comfortable temperatures. Its drainage system helps drain excess moisture outside your home.
When a condensate drain line or drain pan blockage occurs, water builds up in the system and freezes over the coils as the refrigerant absorbs heat. Inadequate maintenance and debris accumulation are typically the reasons for a clogged drain system.
A professional can flush and clean your AC's condensate drain line to get your system up and running again. Regular heating, ventilation and air conditioning (HVAC) maintenance can help prevent these issues from interfering with your unit in the future.
5. Clogged Air Filter
Your air filters could be the cause of your AC unit freezing up. They trap indoor air contaminants and help ensure only fresh, clean air recirculates in your home. A clean filter makes it easy for air to pass through, preventing ice formation on the coils. Clogged filters reduce airflow, which can cause your AC to freeze up.
Periodically changing your air filters is essential to keep dust, dirt and debris from accumulating. It also helps improve your home's energy efficiency. Standard 1-inch filters should be replaced every 30 days.
A pleated filter can usually go six months between changes. However, you should try to inspect it monthly and replace it if you see significant grime buildup. If you're guilty of forgetting this task, stick a note on your fridge or write a reminder on your calendar.
6. Dirty Coil
Dirty air filters can cause dust to stick to your air conditioner's refrigerant coils. These coils can easily collect dust as they become wet from the surrounding moisture. Dust acts as an insulator, making it difficult for cold to escape the coils. This can stimulate ice formation. Thick layers of ice can form as moisture continues to build up.
That's another reason routine maintenance checks are important. Just like air filters, evaporator coils clog up with dirt over time and require periodic cleaning. A professional can help drain the accumulated water from your AC's coils to boost cooling capacity and prevent freezing.
7. Blocked Vent
A simple vent blockage could be causing your air conditioner to freeze up. You may unknowingly block your air vents with large furniture or draperies, disrupting your HVAC airflow. This problem is an easy fix. Simply check to see if anything is blocking your vents, then move it aside. Ensure there is enough space around the vents for proper circulation.
Contact Boss Mechanical for Your Air Conditioner Maintenance Needs
Wondering what to do if your AC freezes up? Boss Mechanical is here to help. We have over a decade of experience in HVAC system installation, maintenance and repair.
Our licensed and trained technicians can provide quality AC service and repair to get your unit back on track. We have the expertise needed to diagnose and address the issue, whether it's a broken fan, clogged condensate drain line, refrigerant leak or another malfunction. Reach out to us today to schedule an air conditioner unit repair!