6 Causes of AC Blowing Warm Air

Discover the common causes of AC blowing warm air and find solutions. Sandium offers expert repair services if your AC is not blowing cold air. Visit us today!

Updated on Oct 22, 2023
5 min read
6 Causes of AC Blowing Warm Air

An air conditioner blows warm hair because the cooling mechanism is not working even though the fan is operating. There are numerous issues that can cause this to happen. The easier problems can be fixed without trouble. However, you should not hesitate in calling a Bay Area professional if you want to diagnose and repair larger problems.

1. Problems with Thermostat

You should always check the thermostat when you are worried about an air conditioner blowing warm air. It could be possible that the temperature is set too high. Kids and other people in the house may accidentally or intentionally change the temperature if they feel too cold. You need to make sure the fan set to AUTO and the thermostat is set to COOL.

2. Clogged Air Filter

Another common problem impeding an air conditioner’s cooling mechanism is reduced air flow. The air conditioner can only function when it has adequate amounts of warm air flowing over the coils. The air filter is designed to remove contaminants and dust from the air. However, when the air filter is clogged with dust and debris, it blocks air from getting inside the system. The coils cannot function when this happens. The system’s fan begins blowing warn air back into the space as a result. You should check the air filter if your system is blowing warm air.

3. Return Vents are Blocked or Closed

Another air flow issue that causes the AC to blow warm air is blocked or closed return vents. Maybe you closed the vent grilles over the winters and never remembered to open them. It is possible that you may have furniture or other obstructions in front of the air conditioner as well. You should take a walk around the space and ensure that all returns and registers are open to allow free flow of air.

4. Leaky or Disconnected Ducts

Return air cannot find its way back into the unit when the duct has cracks, holes or is completely disconnected. This can also cause cooled supply air to escape into the crawl space, attic or walls. It is fairly common for rodents or birds to get into the duct space or for damage to occur during a construction project – it has happened more than once. It’s recommended that you get a professional to take a look at the ductwork.

5. Outdoor Unit Doesn’t have Power

Most air conditioning systems have an outdoor condensing unit. The fan will continue blowing air if the indoor evaporator or air handler unit is fine. However, without the outdoor condensing unit, the air will not be cooled. Hence, the AC may blow warm air. A condenser unit can lose power because of a tripped circuit breaker or a blown fuse.

It’s necessary that you don’t attempt at diagnosing the electrical issues on your own. You should get a trained HVAC expert to take care of it. However, you can take a look at the emergency shutoff switch. It could have been shut off accidentally, cutting power to the condenser unit. This may cause the air conditioner to blow warm air.

6. Dirty Condenser Coil

A critical function of the condenser unit is to release heat outside the house. If the condenser coil is caked with dirt and grime, it may not be able to do this. This will eventually impede the coil’s operation and cause warm air to blow. 

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