Troubleshooting Tips | AC Blowing Warm Air

Troubleshooting Tips | AC Blowing Warm Air

Troubleshooting Tips | AC Blowing Warm Air

During the heat of the summer the last thing you need is an AC blowing warm air on a hot, humid day. The following troubleshooting tips may provide the required solution.

There are a number of potential causes that lead to the AC blowing warm air. However, before calling Cypress Heating and Air Conditioning for AC repair in Katy; the following may provide a simple fix you can provide. If you prefer a certified HVAC technician to service and correct the issue, our technicians will be glad to assist you when the AC is blowing warm air.

Thermostat Settings

People often set the thermostat fan to “run” for various reasons, such as to clear the smoke from a burnt meal, or open a window and bring in fresh, cool evening air. Due to this, check the thermostat, and ensure it is set to “COOL”, and the fan to “AUTO”, with a temperature setting below the room temperature display on the thermostat.

If the fan is set to “RUN” (or ON) rather than AUTO, the fan will run constantly, and when the compressor isn’t pumping, the fan would be running with the AC blowing warm air. On the other hand, if the thermostat is set to “OFF”, the compressor won’t pump cold air at all.

Check Breakers

Ensure the AC breaker in the home’s electrical panel hasn’t tripped to “OFF”. Power surges or issues in the system can cause breakers to be thrown, causing either no function at all or the AC blowing warm air. The affected breaker may be in the home’s electrical panel, or those integrated into the system itself. Depending upon the specific brand and age of the system, there may be circuit breakers/switches in the interior portion of a split system. These may appear similar to a light switch lever, or “mini” circuit breakers.

Turn the power off at the thermostat by turning the heat/cool/off function to “OFF”. Next, ensure the interior breakers/switches are engaged by turning them off and back on. Turn the power back on at the thermostat by setting it to “Cool”, and turn the temperature down to at least 5 degrees below the room air temperature. If the AC doesn’t cool, proceed to the next step.

Located in the vicinity of the outdoor unit there should be a breaker box on the wall behind, attached on or under a deck or porch next to it. Not all systems will have this feature separate from the unit itself. However, if present, this breaker when tripped is a common cause of the AC blowing warm air. Once located, set the thermostat to “OFF”, and turn the breaker off and back to on.

Reset the thermostat to “COOL”, and turn the temperature down. If the AC is blowing warm air after checking the breakers, continue with the next step.

Airflow Restrictions

Airflow restrictions involve issues such as an extremely dirty filter, dirty condenser coil, dirty evaporative coil or blockages restricting the outdoor unit or the indoor return air vent.

Dirty Filter

Check the filter and replace it if dirty. An extremely dirty filter can cause a lack of adequate air flow and can result in the compressor freezing up. A dirty filter will also result in a dirty system and ducts, causing damage to components and excessive dust in the home.

Condenser Coil Needs Cleaning

Depending upon the type of system in the home, for example a heat pump or a split system, the AC will have coils in one or two locations. Ensure the area around the exterior unit is clear to provide adequate airflow. This includes plants, leaves or shrubs or other objects.

Evaporative Coil Needs Cleaning

The interior coil in a split system is called the evaporative coil. The air filter is located in this area, and the evaporative coil is one of the components the filter protects. The coils, (both indoor and out) will require cleaning at some point. A dirty coil in either location can cause reduced performance.

Refrigerant Leak

A refrigerant leak is a common cause of the AC blowing warm air. It will require the services of an HVAC technician to locate and repair, potentially evacuating the system and adding refrigerant. Here’s how to determine low refrigerant:

  • The refrigerant line has ice or “frost” on it.
  • The sound of bubbling or a hissing noise.

A leak is the only potential cause of the AC being low on refrigerant. The refrigerant doesn’t need to be “topped off” – unless the system has a leak. Refrigerant doesn’t get used up, and if it’s low, a leak is present and requires repair. An AC leak can lead to costly damage to the system, or even the need for a new air conditioning installation.

Cypress Heating and Air Conditioning’s certified and experienced HVAC experts can provide for all of your air conditioning in Katy, TX needs. Our HVAC technicians are experienced, certified and highly trained professionals in HVAC repair, installation, and service. If our troubleshooting tips didn’t resolve the AC blowing warm air, contact us to schedule repair. We serve Katy, Plano and the surrounding areas, and are a member of the BBB with an A+ rating.