Summer should be all about staying cool and comfortable, but what if you step outside and notice your air conditioner’s outdoor unit covered in ice? It might seem odd — after all, it’s 85°F outside — but a frozen AC unit in the summer is a common and serious problem. In this blog, we'll explain why this happens, what to do if your AC freezes, and how to prevent it from happening again.
Why Does My AC Freeze in Hot Weather?
It might seem counterintuitive, but your AC system can freeze even when it’s blazing hot outside. Here are the most common reasons:
1. Restricted airflow
When air can’t flow properly through the system, the evaporator coil gets too cold. Moisture in the air condenses on the coil and freezes. Causes of restricted airflow include:
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Dirty or clogged air filters
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Blocked return or supply vents
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Dirty evaporator coils
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Collapsed or blocked ductwork
2. Low refrigerant levels
A refrigerant leak can cause pressure to drop in the system. This lower pressure allows the refrigerant to expand too much and get colder than it should, leading to ice buildup on the coils.
3. Thermostat or electrical malfunctions
Faulty thermostats or electrical components can cause the compressor to run continuously, even when it's not supposed to. That nonstop operation can lower coil temperatures too far and result in freezing.
4. Dirty coils or components
Outdoor condenser coils or indoor evaporator coils covered in dust, dirt, or debris can disrupt the heat exchange process and contribute to freezing.
What to Do If Your Outside AC Unit Is Frozen
If you spot ice on your air conditioner, don't panic — but do act quickly to avoid damaging the system further.
Step 1: Turn off your AC immediately
Prevent further damage by switching off the system at the thermostat. Leave the fan setting ON (instead of AUTO) to help circulate air and thaw the coils.
Step 2: Check your air filter
Inspect your air filter. If it’s dirty or clogged, replace it. Sometimes this simple fix can restore airflow and solve the problem.
Step 3: Inspect vents and return grilles
Make sure all supply and return vents are open and unobstructed. Avoid closing off too many vents in unused rooms.
Step 4: Allow the ice to melt
Give the system several hours to thaw completely. Never try to scrape off the ice because you could damage the coils.
Step 5: Call a professional
Even if your unit thaws and starts working again, it’s important to call an HVAC technician to inspect the system. A frozen AC is often a symptom of a deeper issue like low refrigerant or electrical failure.
Preventing a Frozen AC in the Future
Prevention is key to avoiding unexpected breakdowns during the hottest days of summer.
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Change your air filter every 1-3 months
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Schedule professional AC maintenance at least once per year
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Keep outdoor and indoor coils clean
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Ensure vents and registers are unobstructed
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Monitor your system for signs of low airflow or leaks
Need Help With a Frozen AC in Philadelphia and Delaware Valley?
If your AC unit freezes up this summer, don’t sweat it. The certified HVAC professionals at ECI Comfort are here to help. Contact us today to get your system running smoothly again — before the heat wave hits!
If you live in the Delaware Valley/Greater Philadelphia area and would like to find comfort within your home, visit our website or give us a call at 215 - 245 - 3200 to learn more.
