Does My AC Unit Need Repair If It Froze?

Does My AC Unit Need Repair If It Froze?

During the hottest summer months, your air conditioner is your best friend. It keeps your home cool and comfortable as you try to beat the heat. But sometimes, your air conditioning unit can malfunction and completely freeze up.

If your AC unit froze, it means your air conditioner has fallen below 32*F and ice has accumulated somewhere on the unit. This is a pretty obvious sign that there has been some malfunction and your air conditioner will need repair or replacement.

In some cases, you can fix the issue at home by simply replacing the air filter and removing dirt build-up. Other times, you may likely need to call a professional HVAC technician to diagnose the problem and repair it, it may even make sense to replace the HVAC system entirely.

Keep reading to learn why air conditioners freeze, what to look for, and when to call a technician.

Why Do Air Conditioners Freeze?

Air conditioners freeze for a few reasons. Most often, air conditioners freeze due to an obstructed airflow. AC’s can also freeze due to a coolant leak, dirty evaporator coil, and dirty air filter.

To prolong the lifetime of your air conditioner, you should call an HVAC professional after your air conditioner froze. They’ll inspect your air conditioner to check that nothing was damaged that may need repairs.

Red Flags Of AC Freezing

There are some key indicators of your AC unit freezing besides ice accumulating on the outside of the air conditioner. Even if the outside looks fine, your air conditioner could be frozen inside. This could cause major malfunctions and damage if left unrepaired.

Besides any apparent ice on the outside of your unit, the next most obvious sign is your air conditioner simply not working. Your house will be warmer than usual. Since heat rises, you’ll most likely notice this issue upstairs.

Place your hand over the register and check if warm or cold air blows out. If warm air blows out, you can open the access panel to the evaporator and observe the components. If ice has accumulated on these, your air conditioner froze, likely due to a dirty evaporator coil.

If you hear a hissing sound, you may have a coolant leak which may lead to your air conditioner freezing if it hasn’t already. If you notice a hissing noise and your air conditioner is blowing warm air, your air conditioner has likely already frozen. Any problems with the coolant require professional assistance immediately.

What can you do?

Once you know your air conditioner froze, the first thing you should do is turn off your air conditioner and let it completely defrost. Depending on the circumstances, your air conditioner can take up to 24 hours to defrost.

Air Flow

As we mentioned previously, blocked airflow is the most common cause of your air conditioner freezing. After your air conditioner has completely defrosted, check the air filters. If they are covered in dirt, dust, and other debris, you need to change your filter. Even if you’re not sure if there’s a blockage, you should still change the filters.

To prevent your air conditioner from freezing, we recommend swapping out your filter for a new one every month. You should also schedule a yearly inspection of your HVAC system, in which a professional HVAC technician will examine your system’s airflow and clear any obstructions in your unit and ductwork.

Coils, Fins, and Registers

You should also check the coils and fins to see if they’re blocked with excess dirt and debris. Take a soft brush and gently brush any debris away from the coils. You should also check your registers around your home to make sure they’re not blocked either.

If nothing else seems wrong with the air conditioner, you can turn it on after checking the dirty filter and coils. If it works, you probably don’t need to worry about major repairs, but you should still call an HVAC professional for a quick inspection to make sure.


Sometimes if your air conditioner is low on coolant, it won’t be able to accurately monitor its cooling or pressure. This can result in your air conditioner freezing. Being low on coolant can indicate that your air conditioner is leaking coolant. If you see a puddle of refrigerant, hear a hissing noise from your AC, and/or find that your AC is blowing warm air, you may have a coolant problem.

This is a situation in which you should seek professional assistance. Furthermore, to prevent a cooling leak, you should schedule a yearly inspection of your HVAC system. During the inspection, the HVAC technician will check to see if there are any leaks and catch them before your unit freezes.

Evaporator Coils

Your evaporator coils are part of the system that drains water and moisture from your air conditioner via the condensate lines. Dirt, pet hair, and other debris tend to cling to your evaporator coils which block moisture from escaping the unit. This will cause your coils to freeze. In this situation, you should have an HVAC technician inspect your air conditioner to see if repairs are needed.

J.A. Bertsch

J.A. Bertsch Heating & Cooling offers professional residential air conditioning services throughout Kootenai County. Our licensed AC technicians are equipped with the tools to service any air conditioning system regardless of age or model. Whether it’s the latest Coleman system or an antiquated window unit, our experienced team has training and resources to service them all. Call us today to schedule an appointment at 208-635-5480.

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