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Why Is My Air Conditioner Blowing Hot Air?

air conditioner blowing hot air

Is your air conditioner blowing hot air? If so, don’t panic—this is a common issue, but also one you should address as soon as possible.

First things first: why does this happen? To answer that, we need to take a look at how your air conditioner functions.

In an AC unit, the compressor turns the refrigerant from gas to liquid. The expansion valve then turns it back to gas, cooling the indoor coils. Finally, the AC passes air through these coils, providing a cool breeze.

If your AC is blowing hot air, something in this process is going wrong. Here are the seven most likely causes and what you can do to fix them.

Low Refrigerant Levels

An air conditioner needs a sufficient level of refrigerant to exchange heat. If it doesn’t have enough, it won’t be able to cool the coils adequately.

There’s only one reason for low refrigerant levels: a leak in your refrigerant lines. These lines are part of a closed system, which means no refrigerant will go in or out if your AC unit is operating as it should.

A refrigerant line leak is one of the most common AC issues you’ll encounter. The simplest solution is to fix the leak and refill the refrigerant. You can try to do it yourself, but you’re better off contacting an HVAC technician.

Clogged Filters

To function properly, an AC unit must maintain adequate airflow. When that doesn’t happen, you may see hot air coming from your AC.

One thing that can reduce airflow is a clogged air filter. If an air filter is restricting airflow, the rest of the unit will try to overcompensate for it. That can lead to several AC problems, including blowing hot air.

It’s important to note the difference between a clogged and dirty air filter. A dirty filter will only prevent the AC from blowing cold air. Only a clogged filter can restrict the airflow enough to force the unit to produce hot air.

Needless to say, all you need to do to fix the issue is to replace the air filter. For best results, you should be doing that once a month.

Power Issues

Refrigerant cycle issues aren’t the only reason why your AC unit is blowing hot air. Sometimes, the cause will be electronic in nature.

The first thing you should do is confirm your cables and outlets are fine. That seems obvious enough, but you don’t want to miss anything. If the cables seem fine, the issue may lie in the unit’s fuses or amp breakers.

Both fuses and amp breakers protect your air conditioner from electronic surges. If you have a blown fuse, you may see hot air blowing from your AC. Check the fuse with a voltmeter—if it’s broken, replace it.

Fixing a tripped amp breaker is even easier, as all you need to do is reset it. If the breaker immediately trips again, though, you may have a broken AC on your hands. Consider contacting a professional to inspect your unit.

Faulty Compressor

An AC compressor has a single job: to compress the refrigerant. When compressed, the refrigerant will expand and cool down the coils.

If the compressor doesn’t do the job, the refrigerant won’t fully expand. As a result, the coils will start getting warm, leading to the AC blowing hot air. And since a compressor can be tricky to fix, the best solution is to replace it.

If you have a window or portable AC unit, you may be able to replace the faulty compressor yourself. With bigger ACs, you’re better off letting the professional take care of it for you.

Clogged Expansion Valve

An expansion valve is what turns the refrigerant in liquid form back into gas. That’s what sends “chills” through the coils and cools them down.

If your unit is blowing cold air, you may be dealing with a clogged expansion valve. You can confirm that yourself by testing the valve. Before doing this, make sure that your AC unit is on to provide a source of power.

First, locate the valve by checking the manufacturer’s manual. What you’re looking for is a small bulb joined to a tube connected to the valve body. Refer to your manual to learn how to lift the bulb from the bulb well.

Now, place the bulb in warm water and keep it there for two minutes. The warmth should force the refrigerant to flow into the evaporator. If that doesn’t happen, try replacing the powerhead of the valve.

Broken Condenser Fan

You’ll find the condenser fan in your outdoor unit. When the fan is doing its job, it’s sending the heat from the evaporator coils outside.

If the fan malfunctions, it will stop spinning. That will overheat the condenser, causing a safety mechanism to shut it down to prevent damage to the unit. As a result, your AC may start emitting hot air.

First, inspect the outdoor unit for debris. If it’s clogged up, turn off the unit at the source and remove the debris with your hands or a garden hose. Make sure your outdoor unit has two feet of clearance on all sides.

If you don’t see any debris, the fan motor may be malfunctioning due to the general wear and tear. The simplest fix is to get a new outdoor unit.

Thermostat Issues

Finally, there’s a chance you’ve set your thermostat at a higher-than-room temperature. That’s quite unlikely, but check your settings to be sure.

If you’ve installed a new thermostat recently, there’s also a chance it’s not wired properly. Poorly wired thermostats can cause all sorts of AC issues, including your unit blowing hot air.

If you know what you’re doing, you can rewire the thermostat yourself. Take a picture of the wiring before removing the thermostat. If you’re not an expert, contact a professional AC service to fix the issue.

More on the Air Conditioner Blowing Hot Air

As you can see, not all air conditioner issues are equal. You may be able to solve some problems yourself, but it’s often better to call an experienced technician. Our guide should help you figure out the best plan of action.

Is your air conditioner blowing hot air and you’re not sure why? Our emergency service will diagnose the issue and fix it within 24 hours! Contact us here to learn more about how we can help you.

Sameh t
Author: Sameh t


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