It’s July, maybe close to the 4th, guests are coming, it’s 95° in the shade, and your air conditioner freezes up. What the heck is going on and what can you do to fix it? It helps to start by understanding why the problem occurs in the first place.
Why Your AC Freezes Up
There are four primary reasons for an air conditioner to freeze up. Keep in mind that regardless of the reason, a frozen air conditioner not only cools improperly, but it can result is serious damage to your unit over time—it’s definitely a problem you’ll want to address.
- Low refrigerant. If your system is low on refrigerant (typically Freon for older systems), that will lower the pressure inside the unit. The lower amount of refrigerant still has to expand the same amount, which causes a cooler temperature. And as counter-intuitive as that may seem, that cooler temperature is exactly what can freeze up your system.
- Insufficient airflow. Your AC removes heat from your home by blowing hot, inside air over the evaporator coil. If that airflow is interrupted or insufficient, the proper heat exchange cannot occur. Over time, the refrigerant temperature will drop and the unit can freeze up.
- Operating temperatures. Most air conditioners are designed to run within specific temperature ranges—both indoors and outdoors. If your thermostat is set below 68° F or the outside temperature is below 60°, pressure in the coil will be too low to function correctly and freezing can occur.
- Mechanical failure. Any number of mechanical issues could cause your problem. These include kinks in the refrigerant lines, a damaged blower fan, or clogged filter dryer.
Before you call in the professionals, here are a few DIY fixes you can try.
- Check your air filter. A dirty filter can restrict the airflow through your unit. Replacing your filter regularly is one of the easiest, cheapest means of keeping your system running efficiently. You should replace your filter at least every 2-3 months and more often if needed. Be sure to use high quality filters and always have an extra on hand.
- Check the evaporator coil. If the inside evaporator coil is dirty, that can restrict airflow, dropping the temperature and your unit freezing up. Cleaning the coil and keeping it clean is another step to keeping your AC freeze-free.
- Check your ductwork. Airflow restriction can occur due to closed vents, dirt, or other restrictions in your ductwork. Inspect your ducts for any obstructions, bends, leaks, or disconnected parts. This involves more than some homeowners are comfortable with, so it may be time to call your HVAC pro for this inspection.
When to Call the Pros
If you’ve changed your air filter, checked the evaporator coil, and made sure there’s no airflow restrictions in your ductwork and your AC is still freezing up, it’s time to call your HVAC professional. If you have a problem with your blower fan or another mechanical issue, you’ll definitely want those handled by a pro. If you’re low on refrigerant, most areas have laws that require recharging by a licensed HVAC technician.