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What’s Wrong with My Car’s AC?

You’re planning to drive to your favourite summer getaway spot for a relaxing vacation. Although it’s a long drive, you know it will all be worth it once you get there. You get in your car, turn the ignition, and put it into reverse—then stop. There’s no way you can drive for hours in the heat. Your AC isn’t working.

When your AC malfunctions, there’s not one go-to solution. It could be the result of several problems.

AC Basics

First, make sure you are using your AC system correctly. The AC has several buttons:

  • AC: turns your AC on or off; when it is on, it is cooling the air.
  • Recirculation button (circular arrow): cools air that is already inside your car. This can cool your car faster, but is only necessary during really hot temperatures. It’s also useful if you are driving behind a truck and don’t want to breathe in the fumes.
  • Circulation button (wavey arrows): Circulates air from outside your car. For fresh air, keep your air conditioner on this setting most of the time.

Now that you know how your AC works, let’s look at some common problems.

It Smells Bad

If the airflow is weak or the air smells terrible, there is a simple solution: clean your air vents. Dirt, dust, pollen, spores, and air particles can all get trapped in your vents and clog them.

Fortunately, this is something you can fix yourself in a few steps:

  • If possible with your particular vehicle, remove and replace your cabin air filter. If the smell persists, go on to step two.
  • Turn your AC on to full with the recirculation button on.
  • Spray AC vent cleaner into the exterior air intakes (the ones next to your windshield wipers).
  • Let the AC run for 10 minutes.
  • Turn off AC and spray cleaner into the AC vents on the inside of your car.
  • Let your car sit for 20 minutes with the windows rolled up.
  • If the smell persists, repeat steps two through six.

You can also call upon a professional mechanic to ensure a thorough cleaning.

It’s Not Blowing Air

If your car’s AC system isn’t blowing air at all, there’s likely a problem with the doors and flaps that let the air through its passageways. Depending on your car, the doors and flaps are controlled by different means:

  • Cables and controls. When a cable or control breaks, it prevents the air from flowing toward the correct direction.
  • Electricity. Voltage signals tell the car to open the doors; a faulty control module or electric motor could cause the AC to malfunction.
  • Vacuum. A vacuum leak could cause the air to flow toward the windshield, rather than toward you.

Note that when there is a problem with the engine, your car’s computer may automatically shut off your AC system. An electrical problem in your circuit or clutch can also prevent your AC’s function.

It takes a qualified mechanic to examine your car’s specific system and determine the problem.

It’s Not Blowing Cold Air

Is your AC system blowing air, but the air just won’t get cold? The simplest solution is that there is the wrong level of the refrigerant to cool your air. Both excess refrigerant and a lack of refrigerant can cause problems. If you don’t have enough, it can’t cool the air; if you have too much, the pressure is too high for the compressor to pressurize it and turn it into a liquid.

Thus, a mechanic needs to be extremely careful not to add too much refrigerant. They use a pressure gauge to ensure the refrigerant is between 20 and 30 degrees below the outside temperature. Some people add refrigerant themselves, but this is not recommended, as the process can be dangerous.More often than not, the refrigerant is low because there is a leak in the refrigerant system. How do you tell if this is the case? When you turn on your AC, listen for a click from the engine area. This is the compressor clutch; when you’re low on refrigerant, your compressor will cycle on and off. A hissing sound from your AC system, a damaged condenser, and oil residue around AC hoses and pipes can all clue you in to a leak as well.If you don’t have a leak problem, you might have a problem with the compressor.

Problems could include:

  • Broken compressor belt or electrical circuit
  • Failed compressor
  • Bad control module
  • Defective pressure switch
  • Damaged wiring

If the compressor isn’t the issue, a mechanic may evaluate other components. Your blend air door might be stuck, which can prevent your system from bringing in cold air and might cause it to circulate heat from the engine. Another problem could be a malfunctioning AC fan.

As you can see, there are plenty of potential problems. Speak to a mechanic, who can evaluate and repair whatever is ailing your AC system.

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