Why Your Air Conditioner Keeps Freezing Up (And How to Fix It)
Key Takeaways
When an air conditioner freezes up, it’s usually a sign of restricted airflow, low refrigerant, or mechanical issues that prevent the system from absorbing heat properly. Common causes include dirty air filters, blower motor problems, blocked or damaged ductwork, drainage issues, and setting the thermostat too low on cooler days. Turning the system off to allow it to thaw is an important first step, but addressing the underlying cause is essential to prevent repeat freeze-ups. Regular maintenance, proper airflow, and timely professional service can help keep your AC running efficiently and avoid future problems.
It’s a warm day. You have a warm home. Your AC isn’t blowing cold air. There are all kinds of reasons why this might happen, but one of them is that the coils of your AC freeze up.
This might be an easy fix or a hard one, but knowing why it happens can help you not just fix it, but keep it from happening again.
Unfreezing Your AC Unit
First of all, a quick note on how to get your frozen AC unit working again. You can turn the system off (and should as soon as you notice it’s frozen), turn off the circuit breaker, and leave it until it thaws. Do not try to chip off the ice. Switching the unit to fan-only mode can speed up thawing. Another trick is to blow hot air on the frozen coils using a hairdryer. Hold it about a foot away and set it to the lowest setting. However, if there is an apparent refrigerant leak, don’t try this method. Call a professional.
You also need to address the root cause, or your AC will freeze up again.
Here are some of the reasons for a frozen AC unit:
Insufficient Heat Load
Some people like it cold. If you turn your AC way down on a cooler day, it might freeze because it, ironically, does not have enough heat load…enough work to do. The solution is simple: If it’s cool outside, turn your AC off and open the windows. You’ll save money and energy, too.
Dirty Filters
When did you last change your filters? If the answer is that you don’t know, then it’s almost certainly time to change them. In most cases, homeowners must change air filters every 1–3 months, depending on usage, pets, and allergies. However, if you have pets, you will probably need to change them more often. You should check and clean your filters every month.
If you’re unsure about the manufacturer’s filter change recommendations, consult a professional. They can help establish that for you and give your AC a proper tune-up. Dirty filters cause an AC freeze-up by letting moisture build up inside the unit.
Blower Motor Problems
If your freeze-up is associated with low or no airflow, strange sounds, or circuit breaker issues, it’s probably your blower motor. There are several reasons why it can go bad, so it’s best to have a professional replace the damaged blower motor and check for airflow restrictions. This can be as simple as a vent being blocked by furniture or clogged.
Not cleaning your filters can also result in blower motor problems. Another common issue is a blown capacitor. The fan may also be damaged or wobbly. If the motor won’t turn, it’s probably the bearings.
All of these require expert assistance, but you should also ask about what might be restricting airflow and causing the motor to overheat.
Blocked or Damaged Air Ducts
Blocked or damaged air ducts also slow airflow and can cause freezing. One sign you might have a duct problem is if air is blowing from some vents but not others.
Get your air ducts inspected every year. Cleaning isn’t always necessary, but it’s a good idea if there’s a lot of dust or if you have pets. Pests can also damage your air ducts or block them. Rodents, for example, might build a nest in your ducts. Be ready to involve pest control if needed.
Faulty Condensate Drainage
Dirty filters can cause moisture buildup, but so can drainage problems with the air conditioner itself. Keep your external unit free of outdoor debris, trash, fallen leaves, branches, etc, which can all block the drainage path.
Low Refrigerant
Last, but far from least, an AC freeze-up can be caused by low refrigerant. Low refrigerant pressure means the unit’s temperature can shift, preventing it from transferring heat. If this is the case, then get a professional as quickly as possible. You likely have a refrigerant leak somewhere. This can be a problem with really old systems that use refrigerants that are no longer approved. You may even need to consider an upgrade (and you should anyway; those refrigerants are toxic and harmful to the environment).
AC Freeze Up Can Be Avoided!
If you have a climate control unit that keeps freezing up, contact Mid-Fla Heating & Air. We can help you find and fix the problem and give your system a good tune-up. For optimal prevention, schedule a tune-up and inspection now!
