Icing is a condition where the evaporator coil for the air conditioner ices over and your unit can no longer cool the home properly. The evaporator coil is located in the ductwork, usually just above your furnace. Your furnace fan moves air over the coil and distributes the cool air throughout your home.
Finding ice on your air conditioner might seem strange, especially during a hot summer in London, Ontario. But a frozen air conditioner is a fairly common problem and usually indicates that something is preventing your cooling system from operating properly.
If your air conditioner is freezing up, the problem can range from something as simple as a dirty air filter to an issue that requires professional HVAC service.
Here are some of the most common causes of AC icing and what homeowners in London and the surrounding area can do about them.
Don't set the thermostat too low
Often if an air conditioner is icing, it can be traced to improper use. This is a common problem for new homeowners and it is easy to fix.
If you set the thermostat too low, it can cause the unit to ice. Many people think that by setting a lower temperature it will help to cool down the home faster. That is not how your air conditioner works. If you set the temperature too low, your air conditioner will run continuously trying to get your house to the temperature you set.
The volume and temperature of the air flowing through the coil affects the surface temperature of the coil. As the temperature in the home drops the lower temperature of the air flowing over the coil is not sufficient to keep the surface temperature of the coil, which is being cooled by the refrigerant, above freezing. As a result, the water on the coil (condensate) freezes and air can no longer flow through the coil.
Evaporator coil freezing can also occur if the outside temperature drops quickly and the air conditioner is left running to cool down the home. We often see this if the thermostat is set too low or the AC was left off all day and turned on in the evening to cool the house down. If the outside temperature drops quickly the refrigerant temperature at the evaporator coil is so low, it can cause the moisture on the coil to freeze.
Dirty or Clogged Air Filter
One of the most common causes of an air conditioner freezing up is restricted airflow from a dirty air filter.
When the filter becomes clogged with dust and debris, less warm air can move across the evaporator coil. Without enough airflow, the coil can become too cold and begin to freeze.
Check your furnace or air conditioner filter regularly and replace or clean it according to the manufacturer’s recommendations. During periods of heavy air conditioning use, especially during hot and humid Southwestern Ontario weather, it is a good idea to check the filter more frequently.
Blocked or Closed Air Vents
Your HVAC system is designed to move a certain amount of air throughout your home. Closing too many supply vents or blocking return-air vents with furniture, rugs or other objects can reduce airflow through the system.
Make sure your vents and registers are open and unobstructed so air can circulate properly.
A Dirty Evaporator Coil
Over time, dust and dirt can accumulate on the evaporator coil. This buildup can reduce heat transfer and restrict airflow, making it easier for ice to form.
Cleaning an evaporator coil is generally best left to an HVAC professional, particularly if accessing the coil requires opening the system.
A Blower Fan Problem
The blower fan moves air across the evaporator coil and throughout your home. If the fan is not operating correctly, airflow may be reduced enough for the coil to freeze.
A faulty blower motor, damaged fan or other mechanical problem should be inspected by a qualified HVAC technician.
Low Refrigerant
Low refrigerant levels can also cause an air conditioner to freeze up. When refrigerant pressure drops, the evaporator coil can become colder than it should and ice may begin to form.
Air conditioners do not normally “use up” refrigerant. If the system is low, there may be a leak that needs to be located and repaired.
Refrigerant problems require professional diagnosis and service.
What Should You Do If Your Air Conditioner Ices Up?
- Turn off the air conditioner. It has to thaw out and cannot do this while it is running.
- Make sure all your vents are open.
- Make sure you have a clean furnace filter installed.
- Change your furnace fan setting from ‘auto’ to ‘on’. This will thaw the coil faster.
Preventing a Frozen Air Conditioner
Regular HVAC maintenance can help prevent many of the problems that lead to a frozen air conditioner.
Changing your air filter regularly, keeping vents clear and having your air conditioning system professionally inspected can help maintain proper airflow and identify potential problems before they lead to a breakdown.
For homeowners in London, Ontario, having your air conditioner inspected before the summer cooling season can help ensure it is ready for periods of hot and humid weather.
Preventive maintenance can also help your air conditioner operate more efficiently when you need it most.
Air Conditioner Freezing Up in London, Ontario?
If your air conditioner continues to freeze after checking the filter and airflow, it may be time to have the system professionally inspected.
Salmon Plumbing & Heating provides professional air conditioning repair and service in London, Ontario and surrounding communities. Our experienced HVAC technicians can diagnose the cause of a frozen air conditioner and recommend the appropriate repair to get your cooling system operating properly again.
Contact Salmon Plumbing & Heating to schedule air conditioning service in London, Ontario and keep your home comfortable this summer.
