Why Is My AC Not Cooling?

A poorly functioning air conditioner is a significant problem during Iowa's hot and humid summers. If warm air is blowing from your vents, or the air isn’t as cold as it usually gets, you’re probably wondering what the issue could be.

The primary reasons your AC isn’t cooling could include:

To help restore your home’s comfort, we’ll review each issue and provide tips for resolving it ASAP.

Incorrect thermostat settings may be a minor problem but can cause warm air to blow out of your vents.

Why?

A thermostat set to “ON” will have its fan running all the time and circulating air throughout your home—even when the system is not cooling.

Solution: You’ll want to check that your thermostat settings are on “COOL” instead of “HEAT” and “AUTO” instead of “ON.” A thermostat set to “AUTO” will only have its fan blow air during a cooling cycle.

Air conditioners cool homes by drawing in warm air and stripping that air of heat. The system pulls in this warm indoor air through its air filter.

When the air filter gets clogged with dirt and other debris, your air conditioner won’t be able to pull in enough warm air to cool your home to your set temperature. The less air it pulls in, the less cool your home feels.

A buildup of dirt and dust on the air filter can also lead to other problems, such as a dirty evaporator coil. This air conditioner part is the home of your system’s refrigerant. When it gets dirty, the refrigerant cannot properly absorb heat from the air pulled in. Therefore, the air from your vents will feel warmer, or the cool air will feel less strong than normal.

Solution: Check your air conditioner’s filter for debris buildup. If the filter is dirty, it’s time to replace it. Professionals recommend replacing the air filter at least every 3 months throughout the year and once a month during the summer.

While you can easily replace an air filter yourself, it’s best to leave cleaning the air conditioner’s evaporator coil to the professionals. An HVAC technician has the proper tools and training to clean such a fragile and critical system part without damaging it.

When an air conditioner starts leaking refrigerant, it will have a harder time cooling your home to your desired temperature.

Refrigerant is a cold chemical agent that absorbs the warmth from your home’s indoor air. It takes the heat and dumps it outside. With a refrigerant leak, your air conditioner will not be able to absorb enough heat to properly cool your home.

You can tell if you might have a refrigerant leak if:

• You see a sudden spike in your cooling bills
• You hear hissing or bubbling sounds near your AC system
• You see ice forming on the refrigerant lines connecting the indoor and outdoor units
• You see a pool of water around the indoor AC unit

Solution: If you suspect that your AC has a refrigerant leak, contact an HVAC technician. Only a professional should find the leak, repair it, and recharge the refrigerant since the substance is toxic.

The compressor is an air conditioner part that pumps refrigerant throughout your AC system. It is the "heart" of a system, and a broken compressor will completely shut down cooling.

When air conditioners start to age, the compressor typically endures the most wear and tear. When it stops functioning the way it used to, other AC parts will undergo unnecessary wear and tear in order to compensate, leading to system performance issues.

Solution: Contact an HVAC technician to inspect your air conditioner’s compressor. If it needs repair, ask for a replacement quote as well. Most homeowners choose to replace their systems entirely as compressor repairs are costly. If repairing the compressor will cost 50% of a new system replacement, it might be worth replacing the entire air conditioner instead of continuing to sink money into repairs.