Why is My AC System Blowing Hot Instead of Cool Air?

It’s stressful when you expect your air conditioner in Woodbridge, VA, to blow cool air, but it’s only producing warmth. Consider these common reasons your AC system is blowing warm air and how to solve it:

Thermostat Settings

Your thermostat should control the temperature coming from your vents, and you could have it set incorrectly. First, check to make sure it’s set to Cool and not Heat.

Next, check to make sure the fan is set to Auto rather than On. When it’s set to On, the circulating fan will run all the time, regardless of whether the compressor is running. This will make the air coming from the vents feel warmer than you’d expect.

Dirty Air Filter

Your AC system depends on drawing air in and then pushing it back out after cooling it. A clogged air filter restricts airflow, causing less air to come from the supply vents, which makes it feel warmer.

The key is determining when your air filter needs replacing before it restricts airflow. In homes with average air quality, pleated 1- and 2-inch filters need replacing about every 90 days. Plan to check your filter monthly to ensure you keep the right amount of air flowing through your system.

Low Refrigerant

Your air conditioner is a sealed system, so it shouldn’t leak any refrigerant unless there’s damage. Even a small leak affects how much heat the refrigerant can absorb from within your home and then vent outside. It can also lead to frozen evaporator and condensing coils, further inhibiting your AC system’s cooling function.

Annual maintenance is the best way to regularly check the level of refrigerant in your AC system. Even slightly low refrigerant may mean that you have a damaged compressor or a leak in a line or coil.

Clogged Coils

Your AC system has two different coils that allow it to both absorb and vent heat, one inside and one outside. Your inside coil can easily clog with contaminants that flow through your filter or come in through leaks. Grass, pollen, dirt, or even weeds growing up along the unit can clog the outside coil.

Part of annual maintenance is deep cleaning that includes your indoor evaporator coil. For your outside condensing coil, be sure to keep debris cleared back at least 12 inches. Take a few minutes to gently flush the outside of the unit with your garden hose without a spray nozzle.

Malfunctioning Fan Motor

Your circulating fan motor is responsible for both drawing air into your AC system and pushing it back out. Spinning slower than normal is a common symptom of a failing fan motor. This reduces the amount of air circulating and has similar effects to a clogged air filter, making the air coming from your vents feel warmer than normal.

Your maintenance service technician will test your circulating fan motor, including electrical resistance and the fan balance. This ensures the motor is spinning at the appropriate speed to effectively circulate air and cool your home.

Burned-Out Compressor

The compressor is responsible for compressing the refrigerant, which raises its temperature. This allows it to expend the heat it absorbed in the evaporator coil inside. If the compressor is failing, it cannot raise the refrigerant’s pressure enough to vent the appropriate amount of heat.

Compressors should last the entire life of your air conditioning unit, but a few things may make them go bad. If there’s a manufacturing defect, it’s usually apparent while the compressor is still under warranty, which is annoying but covered.

The bigger culprit leading to compressor damage is low refrigerant. Even a small leak will strain the compressor, causing it to burn out prematurely. Finally, the compressor may have sustained damage due to a natural disaster like a flood.

If your AC system isn’t producing cold air, it won’t suddenly fix itself. Call to schedule your AC repair appointment with one of the expert service technicians at Brennan’s Heating & Air Conditioning today.

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