AC Blowing Hot Air: Why And What To Do

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The summer is a perfect time to give yourself instant cooling as you drive through the Las Vegas hot weather.

With temperatures rising to 100 degrees Fahrenheit, you can’t afford an auto air conditioner (AC) blowing hot or warm air. Driving around this city requires a cool breeze most of the year.

So, if your car Ac blows hot air, there’s an airflow issue already. But there are things to indict, really, with the prime suspects being low refrigerant, clogged air filters, and thermostat problems.

Suffice to say that the AC is an essential component of the car -in and out of season. Sometimes you’ll need it to blow warm air, especially during winter. At other times, it needs to provide 100 percent breeze and cooling.

What causes the AC to blow hot air? What are the possible fixes? I’ve got magic answers for you. Let’s get into the fray.

AC Blowing Hot Air: Reasons And Solutions

Here are possible reasons your car AC is blowing hot air:

Clogged Air Filters

When the air filter is clogged, it causes many issues for the air conditioner. First off, a blocked HVAC filter will put more pressure on the system as the AC works harder than normal to keep up.

As a result, the system will overheat. In addition, when the air filter is dirty, there is increased energy usage due to higher pressure demands.

A dirty filter produces unhealthy and stagnant air, resulting in duct-bound cool and warm air blockade. The evaporator coil will freeze, and the AC will start to blow hot or warm air.

How To Fix

When you notice that the HVAC system filter is clogged, the first thing to do is unclog it.

You can do a DIY cleaning of the filter. A certified technician can also help you replace the filters. Overall, it is recommended to clean the filters once in three months.

Here’s a guide to DIY air filter cleaning:

  • Switch off the AC unit to prevent the circulation of dirty air
  • Take off the filter
  • Use a hand vacuum cleaner to lift allergens off the filter
  • Wash, wipe, and rinse the filter
  • Re-install the filter

Low Refrigerant Level

Low refrigerant is another common reason your AC is blowing warm air. The refrigerant is the term that refers to the chemical blend cycle in the AC.

Located in the AC system, the fluid moves inside two sets of copper coils, one outdoors and the other indoors. The refrigerant soaks up heat from the indoor coil to cool the air. From there, it transitions outdoors to release the heat.

As the process repeats, the refrigerant changes from a high-pressure liquid to a low-pressure gas and vice versa. When the AC fan blows hot air, it releases the air over the coil at the other.

When the refrigerant loses its charge level through leaking, it will become low. When this happens, the unit’s cooling power is endangered, causing a pressure change in the system. Ultimately, the compressor can damage.

How To Fix

The thing to do when your AC refrigerant’s charge level is low is to call your technician. A certified professional will be able to tell where the leak is coming from.

A leaking refrigerant is a risk to your health and safety. One of the possible issues may of a leaking refrigerant is a damaged AC unit or the ozone layer. To prevent refrigerant leaks, try to either patch the coil or replace it.

Failing Compressor

The compressor is considered the heart of the AC unit. Once it’s faulty, your AC won’t work. If the Freon level is perfect and the other issues above don’t surface, you may need to check the compressor.

The job of the compressor is to fully compress the refrigerant. The expansion takes the Freon from gas to a liquid, making it cool down the cooling coils.

A faulty compressor will cause incomplete Freon compression and expansion. If the cooling coils don’t properly cool off, the AC will start to blow warm.

How To Fix

Let me warn you that fixing an AC compressor isn’t something within your remit. In most cases, an HVAC technician will advise you not to repair but replace the compressor if it’s badly damaged.

But the good news is that replacing the compressor is cheaper and simpler. You can replace the compressor if your AC units are portable or you’re using a smaller window.

You can find the compressor in the outdoor unit of the AC system.

Frozen Evaporator Coils

If the AC evaporator coils freeze, it causes the AC system not to blow cold air. The evaporator coils are filled with fluid called the refrigerant and installed in the unit.

The coils act like a sponge that absorbs heat from the indoor air. Once the sponge is frozen and clogs the airflow, the evaporator will get too cold.

As a result, ice will build up, leading to the release of warm air. Sometimes, you may not notice any airflow. For the coils to work properly, warm air must go around the coils.

How To Fix

The evaporator coil will freeze when the air filter is dirty and clogged. While you may apply a DIY method to remove, clean, and replace the air filters, cleaning the coils isn’t easy.

Hence, you will need the service of a technician to tide up the coils. Any improper handling can cause the coil to destroy, and that will be a frightening cost on your part.

An Issue With The Thermostat Settings

Every component of the AC system is crucial to proper functioning. However, the thermostat AC blowing warm air indicates that the thermostat is incorrectly set up or badly damaged.

One reason the thermostat might have an issue is an incorrect calibration of the units. Improper setup can cause the thermostat to misbehave.

However, there are other reasons the thermostat may have issues.

There are two areas to look at when you experience wrong calibrations. It might be that the thermostat is calibrated to ‘heat.’

Alternatively, there’s the chance that the thermostat fan is switched on or off instead of ‘auto.’

In the first case, you may have mistakenly turned the thermostat switch from ‘cool’ to ‘heat.’ If the fan is put at ‘on,’ it’ll blow warm air.

How To Fix

The first thing to do is troubleshoot to see if the thermostat settings are wrong. Put the fan to an “auto” mode instead of the “on” mode. Set the thermostat to ‘cool’ instead of ‘heat’ mode.

A wrong setting will automatically work the fan even if the air is set to blow cooling. If any recalibration solution doesn’t work, you may need a technician.

Clogged Orifice Tube

Besides clogged air filters, another reason hot air is coming from AC is a clogged orifice tube. Also called the expansion valve, the tube, as you’ll come to know, helps return the high-pressure Freon from liquid to gas.

Thus, it releases and expands the liquid Freon to gas. The cooling coils receive chills or a cooling breeze during the expansion process. This way, the cooling coils will cool down.

However, once the tube is clogged, the refrigerant won’t adequately expand to gas, so the cooling coils won’t cool down as they should. The result is that your car’s air conditioner will blow warm or hot air as it runs.

How To Fix

The thing to do is to remove the clog blocking the Freon’s passage and preventing its full expansion to gas. It’s best to call on a professional HVAC expert. They will unclog the valve and get the Ac unit back to normal functioning.

An Issue With The Fans

The fans are an essential part of your car’s AC unit. A faulty fan engine can cause the fan not to work properly. If the fan belts are worn, the fan may also fail.

You can check if there’s not enough lubrication around the fan. If there is dirt or debris around the fans, they may prevent them from functioning well. All of these are reasons the fan won’t perform its role.

So, what happens if the fans fail to work? The two fans are located in the outdoor and indoor units of the AC. Once they fail to work, airflow will be limited, leading to Ac blowing hot air.

You won’t receive the cool breezes that you expect. If the fan problem lingers, the compressor can fail.

How To Fix

As highlighted above, there are various reasons your AC fans won’t work. If the fan motor is damaged, you’ll need to replace it. It may also be that it needs proper cleaning to take off the dirt.

If the blades are dirty, you can also clean them using a piece of smooth, damp cloth.

Clogged Drainpipes

For car Ac blowing hot air, it must be that the drains are clogged. Typically, when the AC removes moisture from the air, it exhausts it through a drain line.

The lines may become clogged by dirt, debris, or deposit, thus blocking the expulsion of the moisture. As a result, the water will get to the drains and return to the source.

When this happens, it will damage the AC system and cause it to blow warm air. In fact, the water can leak and goes through other ways, forming mold.

How To Fix

Clogs in drain lines may be easy to remove and flush if visible through the drainpipe. With a protected hand, you can easily take off the debris. However, you can pour a vinegar formula into the pipe once a month to prevent the buildup of dirt.

Duct Leaks

Added to the issues above are duct leaks. If there is an issue of leakage with the ducts, the AC vents may blow warm or hot air.

Primarily, the car AC ducts help circulate the air that gets into and out of your car from the heating and cooling systems. In fact, the air that circulates in and out of your car daily passes through the ducts.

Any leaks in the duct may be due to incomplete or reckless installation. Hence, you won’t feel the consistent interior comfort that the AC offers.

How To Fix

The thing to do is to install an overflow switch. This device halts the function of the entire AC system. While you’re doing this, you can place a call to your HVAC professional to take a look at it. It may need repair or replacement.

Frequently Asked Questions

How Does Car AC Work?

The AC compressor changes the refrigerant from gas to liquid, causing the system to release heat. The condenser takes the heat away from the refrigerant and directs it toward the expansion valve. The liquid Freon turns to gas as it passes through the expansion valve orifice tube.

In the process, the evaporator transfers heat to the refrigerant. The orifice tube helps return the high-pressure refrigerant to its gaseous state. This comes after the evaporating component has pulled heat from the air.

The surrounding of the evaporating serves as the cooling coils responsible for cold airflow and cooling. The evaporator cools the indoor coils down as air pass through them to provide you with a cooling breeze.

Can I Know If My Car’s AC Is Cooling?

Yes, you can detect if the air conditioner is cooling. All you need to do is insert a thermometer close to your registers. Take the readings to tell if the AC cooling coils are cooled down.

On average, the air of a normal auto AC is cooled to 38 degrees. If you set the temperature higher than this, you’re making it pretty difficult for the AC system to work. Hence, it will be forced to reheat the cooled air.

What If My Car AC Isn’t Cooling Enough?

The thing to do if the AC in your car isn’t cooling enough is to trace what the reasons could be.

The thermostat or refrigerant might have issues. You may need to inspect the evaporating coils to see if they’re clogged and need to be cleaned.

An AC system covered in debris and dirt will prevent heat transfer and won’t cool the cooling coils as expected.

Final Considerations

AC blowing hot on a hot day threatens your safety and health. Any faulty component can cause the AC to blow hot.

If you notice any issue with the condenser, compressor, or cooling fans, it’s time to take them out for repair.

There are some issues you can easily fix. Others, you may need to contact a certified AC technician.

In addition, to the reasons mentioned above, you can also check if the outdoor AC unit is obstructed.

Whatever the case, you’ll need the Ac to be in perfect condition all the time. Don’t take anything for granted, as it may take a serious toll on your safety and health.