How to Fix Your Car's Air Conditioner

There are few things worse than finding out that your air conditioner has gone kaput on a hot day
Written by Brenna Swanston
Reviewed by Carrie Adkins
There are many problems that could potentially hamper your car's AC system. The good news is, most of these problems can be fixed without requiring professional help.
So, is your car's air conditioner emitting a funky smell? Or is it blowing warm air even when it’s cranked up to full blast?
Here are some common car air conditioning problems and how to fix them.

How to get rid of musty smells in your car’s air conditioner

A blower fan circulates hot air from the car’s interior into the air conditioner’s evaporator. The evaporator is tucked away under your car’s dash. It goes without saying, but the air within the evaporator is damp, which creates an ideal environment for mildew and mold growth.
That means, if you're cranking up the AC and getting a whiff of something funky, odds are, you're smelling the mildew or mold in your car's evaporator.
To get to the bottom of the smell, check to make sure the evaporator is draining correctly. Sometimes, the drain tube can become kinked or clogged, preventing water from getting out.
If the drain tube isn’t the culprit, you might be able to solve the problem by simply airing out the evaporator. This can be done by switching the AC to vent while driving with the fan on for a half-hour or longer.
Sometimes, a musty smell signifies a dirty air filter. They clog up with dust, lint, and outdoor debris that can fall in the space between the windshield and the hood. Check your filter often. If it's dirty, replace it.

How to add refrigerant to your car’s air conditioner

If your vehicle’s air conditioner begins to blow warm air, instead of cool air, that’s a sign you’re low on refrigerant.
Refilling refrigerants is typically an easy task. Here are the steps:
  1. Attach a dispenser to the refrigerant can. The dispenser valve controls the release of the refrigerant and includes a gauge for safely monitoring the pressure.
  2. Before adding the refrigerant, confirm that your car’s compressor is working properly. Do so by starting the car and turning the AC on max. Pop the hood of the car and find the compressor located near the engine. You should see the pulley band on the compressor spinning.
  3. Attach the dispenser to the fill port. The refrigerant fill port is on the left of the engine. Avoid touching the engine as it could be extremely hot.
  4. Slowly release the valve to allow the refrigerant to flow in. Monitor the pressure when the valve is open. The correct pressure will depend on the air temperature around you. The refrigerant will include instructions detailing the ideal pressure for the temperature range.
  5. Allow the pressure to stabilize in order to get an accurate reading. Once the gauge displays your target pressure, disconnect the dispenser.
  6. Test the output from the AC. If done correctly, the air should now be blowing cold. Your refrigerant levels should remain adequate for the next 6 months to a year, unless, of course, you have a leak.

How to find refrigerant leaks in your car

It’s not always easy to determine the origins of all the drips below your car. If you suspect you have a refrigerant issue, a leak detection kit can help. Detection kits work by running a dye through the air conditioning system. As the dye works its way through your car's air conditioning, any leaks from faulty tubes or cracks will be easy to pinpoint.

When to consult a mechanic

If your leak detection kit finds a leak, it’s best to let a mechanic handle the repair. Likewise, if you’ve discovered issues with the air conditioner’s compressor, it’s better to
hire a professional
than trying to fix it on your own. While you may be tempted to try to fix it yourself and avoid the expense, you run the risk of causing even more damage to the air conditioner and other automotive functions.
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