AC Unit Frozen?

When your air conditioner freezes up, it’s typically due to one of the following common culprits:

  • Poor airflow
  • Low refrigerant levels
  • Refrigerant leaks 
  • Thermostat issues
  • Fan problems
  • Extreme outdoor temperatures  

Signs of restricted airflow

Restricted or poor airflow in your AC unit can result in freezing. When airflow is limited, the moisture in the air condenses and freezes on the evaporator coil, leading to ice buildup. This can be caused by a clogged air filter, closed or blocked vents, or obstructions around the AC unit.

Low on refrigerant? 

Refrigerant is responsible for absorbing heat from the air and cooling your home. If your AC unit is low on refrigerant, it can lead to freezing. Low refrigerant levels are often indicative of a leak in the system. A leak is not a situation you should attempt to fix with DIY solutions. AC unit leaks should be handled by the professionals in order to avoid further damage.

Thermostat issues

If your thermostat is set too low, this can result in your AC unit running excessively. Excessive running can lead to freezing. A faulty thermostat sensor may result in inaccurate readings and, in turn, the system may not cycle on and off properly. It is a good idea to check your thermostat settings regularly to avoid excessive running.

Fan problems

An internal fan is responsible for blowing air over the evaporator coil which allows for proper cooling and air flow. A fan that is not functioning properly is a likely reason for AC freezing. Fan problems can result from a faulty motor, loose or damaged fan belt, or problems with the fan control board. 

Extreme outdoor temperatures 

Very low temperatures or high humidity levels can result in AC unit malfunction. When temps drop too low, the refrigerant in the system may not absorb enough heat to prevent freezing. By contrast, high humidity can cause excess moisture that accumulates and freezes on the evaporator coil.  

How to Unfreeze Your Air Conditioner

So, you’ve noticed that your AC unit is frozen. What’s next? Let’s see if we can find a way to unfreeze it. 

Ice on your air conditioner might look worse than it really is.

Turn off your AC unit. Running a frozen AC unit can cause more damage. Next, check the air filter. If the air filter is clogged or dirty this will impact air flow. A dirty air filter should be replaced. Always follow manufacturer’s guidelines when changing out a filter. 

Look for obstructions. Obstructions blocking the AC air vents can cause malfunction and are a safety hazard. Be sure to remove any outdoor debris blocking the vents, as well as indoor curtains or decor that could block proper air flow or pose a safety concern. 

If there’s ice on your AC unit, let it thaw. Letting the ice melt naturally is the preferable method. It can take several hours (depending on the level of ice buildup) and requires patience. You may want to place a bucket below the unit to capture any dripping water as the ice melts.

Check the unit for refrigerant leaks. If you notice a loss of cooling power or a hissing sounds coming from your unit, this is a sign of a refrigerant leak. If you suspect there may be a leak, call an HVAC professional to manage the situation. Do not try to repair a leak on your own. An AC professional can safely detect and repair leaks, and ensure the unit has proper levels of refrigerant. 

Check the thermostat. After the unit has thawed and the ice has melted, check the thermostat settings. Set the unit to an appropriate temperature and check that the sensor is working properly. It may be necessary to calibrate or replace the thermostat if the sensor is having issues. 

What AC Issues Require Professional Assistance?

It is important to remember that there are several AC problems that you should not try to tackle on your own due to safety risks. 

Reasons to contact an HVAC professional include:

  • Persistent freezing
  • Refrigerant leaks
  • Repairs 
  • Electrical issues

When considering repairs, if you're unsure or uncomfortable with the process, it's always a good idea to seek assistance from a professional HVAC technician. They have the expertise and knowledge to address AC freezing problems effectively and safely.

Frontdoor has a team of HVAC Experts who can help determine what's wrong with your AC unit and provide you a list of local, vetted Pros from our network to make the repair. 

Contact Frontdoor for Professional Assistance  

Struggling to fix it on your own? At Frontdoor, we‘re here to meet you in the moment with an Expert on screen, a Pro in person and the right resources at the right time. You can video chat with a plumbing, electrical, appliance repair, HVAC, or handyman Expert in real-time who can help answer your questions and guide you through next steps. The best part? You get your first video chat for free when you download the Frontdoor app

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