Why is my air conditioner blowing hot air after running a long time?

There are few things worse than getting your home or office to a comfortable temperature and then having your AC malfunction. But you don't need to have a meltdown; as long as it's blowing air - even if it's warm air - there's hope that it's a minor technical problem that won't require a costly parts or system replacement. Here are some of the most common reasons for an AC unit to start blowing hot, and what you can do to solve the problem.

Air Conditioner Blowing Hot Air

Things You To Check On Your Own

The most common causes for AC problems stem from not having the unit serviced before starting it at the beginning of the warm season, running it full blast, or from simple human error. Regular pre-season servicing will keep your AC running efficiently, and it will allow a technician to spot potential problems before they become costly repairs. Running your air conditioner full blast can cause a range of problems. Not only does it put to much strain on your parts and system, it will cause the whole unit to wear out and need replacement long before it's intended life should be over.

Freezing Up Your Air Conditioner

People run their AC full-tilt for one of two reasons: either the outside temperature is extreme or they turn the unit off when they're not at home and blast it when they return. Both can cause the AC to work too hard and allow the evaporator coil to fall below 32ºF, causing the water droplets that gather inside the unit to freeze on the mechanism instead of evaporating. If ice builds up in your air conditioner it will block the flow of air and prevent cooling. When you keep the temperature set at a consistent level and avoid turning the AC on and off, your unit will run at an even pace and keep a comfortable, steady temperature without over-taxing the system. Experts recommend leaving it set between 76º - 78ºF for warmer climates like Florida while it's in use.

Be Sure The Heat Is Not On Accidentally

Homeowner oversight is also a pretty common issue. Someone may have bumped the thermostat and accidentally set it on warm instead of cool, or you may have forgotten to reset it when winter ended. You can avoid this problem by pre-setting it to a moderate temperature and flipping the switch to auto so it starts when that temperature is reached. Other times the problem is as simple as a clogged air filter or tripped breaker on the outside unit.

Check The Breakers

A breaker just needs to be flipped back on, but if it happens repeatedly, you should have a repair technician take a look to rule out electrical problems. Any system in the home that requires the free circulation of air, whether it's your refrigerator, dryer, or heat pump, needs to have the filter changed regularly. Even if your home or place of business isn't particularly dusty, neglecting the filter will lead to internal systematic freezing and a lot of hot air. Change the filter once a month in the summer and every six weeks in the winter, if it's a combination heating and cooling system.

When It's Time to Call a Technician

If, after checking the temperature, breakers and air filter, your system still isn't running right, the problem may be one of the following:

- a refrigerant leak

- a bad compressor

- faulty wiring, or improper installation, if the unit is new

Unless your system if very old or not well-maintained, all three of these problems are usually caused by overheating due to heavy use. The life of a heat pump or central AC unit is usually between 12 - 15 years; individual parts may last as long as 10 years with regular service and proper usage. If your unit is new, it should still be under warranty from the HVAC company that installed it; parts are guaranteed against defects by the manufacturer for up to two years from purchase. Make sure that you keep your warranty and receipts in a safe place after installing a new AC. Anything not still covered by the manufacturer or installation company needs to be serviced by a professional HVAC technician.

There's no reason you have to suffer from the heat. When your AC starts blowing warm air, check for the simplest solutions first. If checking breakers or changing the air filter doesn't solve the problem, have a professional look at your system as soon as possible. Unless your unit is old or damaged, the problem can usually be taken care of quickly so you can have your space feeling cool and comfortable again in no time.