Why Your AC Is Freezing Up: Top Summer Causes & Fixes

When summers hit the high 70s, even Tacoma’s mild climate calls for a good AC. However, the mix of high humidity and warm temperatures can cause your air conditioner to struggle. If you’re wondering why your AC unit is freezing up in the summer, we’ll explore the most common causes and troubleshooting tips to get your system back on track.

What It Means When Your AC Freezes Up

When your AC freezes up, the evaporator coils inside the system have dropped below freezing levels. This causes any moisture in the air around the coils to turn into ice, which is especially common in Tacoma’s humid climate. When the evaporator coils become coated in ice, warm air can no longer reach them, and your AC isn’t able to properly cool the air.

Top Causes of a Frozen AC Unit

Discover the top causes of an air conditioner icing up so you can get to the root of your cooling troubles.

Restricted Airflow

When airflow is restricted inside your air conditioner, the evaporator coils lose functionality. This means your AC can’t cool your home, but it also means the inside of the system gets too cold and freezes over. The most common causes of HVAC airflow issues are dirty or clogged AC filter problems, blockages in your vents and ducts, or issues with the blower motor and fan.

Low Refrigerant Levels

It might seem counterintuitive that less refrigerant means more freezing, but low refrigerant is one of the most common causes of an AC freezing up. When a leak in the unit causes refrigerant levels to drop, the overall pressure inside the system decreases and refrigerant can’t move properly, leading to frozen evaporator coils. You should always call a pro for residential AC repair if you notice low AC refrigerant symptoms like visible ice or chemical smells, since refrigerants are toxic if touched or inhaled and pose a significant safety risk.

Thermostat Issues

If your thermostat isn’t running properly, it can direct your AC to work too hard and freeze the system. Sometimes this can happen from a simple incorrect setting, or there may be a problem with the thermostat. It’s important to check thermostat placement — if the thermostat is located directly beside a window or door, in front of a vent, or in a beam of sunlight, it can take an inaccurate reading and lead to unpredictable temperatures.

Dirty or Leaky Ductwork

While dirty ductwork can restrict airflow and make it hard for your AC to work properly, leaky ductwork can send your system into overdrive. When your ducts are leaky or broken, your AC has to work extra hard to send air through the system and cool your home. This can cause your AC to freeze over, as well as drive your energy bills up and decrease overall system lifespan.

Signs Your AC Is About to Freeze Up

Keep an eye out for these common signs that your AC might be in trouble:

• You notice less air coming out of your vents.
• Your home feels warmer than it should.
• The AC is running constantly but not properly cooling your home.
• You notice frost or water pooling around your AC unit.
• You hear hissing or bubbling sounds coming from your AC.

How to Fix a Frozen AC Unit (Short-Term Steps)

If your AC isn’t cooling properly, HVAC summer troubleshooting tips can help you find the problem. Learn how to fix a frozen AC unit with these three simple steps:

Step One: Turn Off the AC

Before you attempt any AC repairs, always turn the system completely off. Shutting off power at the breaker is the best way to guarantee that the system is off and safe for troubleshooting. Allow the ice to melt from your AC, which can take anywhere from two hours to a full day depending on the extent of the freezing.

Step Two: Clean or Change the Air Filters

Check that your AC filters are clean and fresh. It’s recommended to clean your AC filters at least once a month, and change them every three months, following the manufacturer’s recommendations.

Step Three: Check Your HVAC Vents

If you have a central AC system, check around all of the vents to make sure there’s nothing getting in the way of proper airflow. Keep an eye out for common culprits like rugs and furniture that may have been moved in front of vents.

When to Call a Professional HVAC Technician

If you’ve changed your air filters and checked that all the vents are open but your AC still isn’t working properly, it’s time to call a pro. Running an air conditioner with frozen evaporator coils poses a risk to the system as well as a safety hazard, so hiring an experienced technician is the best way to make sure the job gets done right. It’s also a good idea to call for emergency AC repair near you if you notice other problems like:

• Inconsistent temperatures or no cold air
• AC blowing warm air
• Loud noises like grinding, bumping, or whining
• Bad AC smells including burning or chemical odors
• Unexplained rising energy costs

While an experienced pro can fix most AC issues, even the best systems have an expiry date. If your AC is older than 15 years and suffers a major breakdown, a technician can talk to you about AC repairs vs. a new AC installation to help you find the most efficient and cost-effective solution.

How to Prevent Your AC from Freezing Up

Keep your AC running smoothly with these easy AC maintenance tips:

• Change air filters regularly to allow for proper airflow.
• Make sure vents are clear and not blocked by any rugs or furniture.
• Regularly check the condensate line for clogs, and clean it if necessary.
• Clear debris like vegetation and dirt away from the outdoor unit.
• Schedule annual maintenance with a professional to keep the unit clean and efficient.

Why Tacoma & Puget Sound Homes Experience This Issue

The Pacific Northwest’s humid climate can put a strain on air conditioners, contributing to a range of problems including AC freezing up. The damp air can lead to clogged air filters and drain lines, which restrict airflow and force moisture back inside the system.

Another common problem is running the AC when it’s too cold outside, especially in Tacoma summers when the nights are often below 60°F. The evaporator coils don’t have enough warm air to keep them at the appropriate temperature, so they freeze up overnight.

Call Kliemann Brothers for Expert AC Repair

When you need AC repair in Tacoma, WA, Kliemann Brothers is your go-to for expert solutions. Our team of experienced pros is on hand for local AC repairs and replacements, servicing everything from frozen air conditioners to new AC installation following total system breakdowns. Contact us today to book your next appointment and we’ll send out a technician to get your system running like new.