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Car Air Conditioner Maintenance: 4 Troubleshooting Tips

Car Air Conditioner

Summer time is in full effect and it is hot out there! Soon, you’ll be slipping behind the wheel of your vehicle, starting the ignition and powering on the air conditioner. But what do you do if the A/C is blowing hot air or, worse yet, not functioning at all? Forego the perspiration and get some inspiration—here are four tips on how to fix the air conditioner in you car:

Air conditioner1. Examine the Cabin Air Filter

Your car’s cabin has an air filter, which expedites the flow of air from the air conditioning system under the hood and into your vehicle’s interior. A clogged cabin air filter can severely limit the flow of air through the AC evaporator core. It’s easy to check your cabin air filter. That filter is located either inside your glove box, under the dashboard or under the hood. When in doubt refer to your vehicle owner’s manual for the exact location. Wherever it may be, locate it and pull it out. You will know that it is clogged if it is blackened and filled with debris. Replacing it may be all it takes to resolve your car air conditioner problem.

Not every vehicle has a cabin air filter though, so that might not be the problem.

2. Raise the Hood and Check the Condenser

Under the hood, immediately in front of the radiator, sits another part prone to clogging: the AC condenser. Fortunately, you don’t have to remove the condenser to clean it and free up air flow. Instead, simply put a garden hose on a medium to high setting and direct the water flow through the grille’s louvers. The lower portion of the grille is an especially important target, as that is where contaminants like road salt will collect.

You can also check the condenser for any physical damage. Sometimes a piece of debris may strike the AC condenser and bend the paper-thin fins. If you can’t see through the AC condenser due to bent fins, you can fit them easily with a fin comb. This plastic comb has various different size teeth to match, so just find the one that best matches the spacing of your AC condenser fins. Simply comb the fins straight gently with the comb to return the AC condenser back to the way it was. You may not be able to match the factory wavy appearance, but the important part is to allow air to flow through again.

3. Check the Cooling Fan

What do you do if there is no cool air coming out of the vents at all? Today’s modern cars are usually equipped with under-the-hood electric cooling fans so when the air conditioner is on, the cooling fan is working. If it isn’t working, then either the relay, temperature sensor, control module or fan motor has malfunctioned. In most cases, the relay is to blame for shutting down your air conditioner. Visible signs of corrosion or burnt wiring are a sure indicator that the relay should be replaced. When diagnosing an electric cooling fan issue, always keep your hands clear of the fan blades. Some vehicles will switch on the cooling fan even if the engine is not running.

Older vehicles that have an engine driven cooling fan attached to the front engine accessory drive system can still have problems. The fan clutch can fail preventing the fan from spinning fast enough to draw air through the AC condenser and radiator. With the engine off, give the engine cooling fan a spin. It should not spin easily. If it spins easy like a windmill, the fan clutch has likely failed. If the vehicle is really old it may not have a fan clutch at all. If that is the case, the culprit may be the wrong fan being used or a lack of a fan shroud.

4. Examine the Compressor

Another critical component in the car air conditioner system is the compressor. The compressor is tasked with handling low-temperature refrigerant gas and compressing it into a high-pressure, high-temperature gas. When the compressor is working, it sends refrigerant to the condenser. The compressor pulley should be turning if the serpentine belt is turning. In the center of the AC compressor pulley is the compressor clutch. The compressor clutch should spin when the AC is turned on, then cycle on and off as needed with an audible click. If you turn on the AC and the compressor clutch never engages, you may have a problem with the clutch relay or the clutch relay wire. If the compressor clutch engages and is followed with a loud knocking or no noise at all, and no cooling, then the compressor piston may have broken.

Other possible problems could be a bad thermostat, bad clutch oil or low refrigerant levels, which can cause the compressor to shut down. Unless you have the tools and the expertise required to address these issues, your compressor problems should likely be left to the professionals.

Troubleshooting Considerations

Although some air conditioner problems can be resolved using common hand tools, more complex problems may require air conditioning testing, scanning and specialty tools, something not every weekend mechanic owns. This is especially true if a repair necessitates opening the AC system which requires special equipment to reclaim the refrigerant. When in doubt, take your car to a mechanic—a wrong move could do further damage to the air conditioning system.

Check out all the air conditioning system parts available on NAPAOnline or trust one of our 17,000 NAPA AutoCare locations for routine car A/C system maintenance and repairs. Or, for more information on automobile air conditioning repair, chat with a knowledgeable expert at your local NAPA Auto Parts store.

Image courtesy of Flickr.


Matthew C. Keegan View All

Matt Keegan has maintained his love for cars ever since his father taught him kicking tires can be one way to uncover a problem with a vehicle’s suspension system. He since moved on to learn a few things about coefficient of drag, G-forces, toe-heel shifting, and how to work the crazy infotainment system in some random weekly driver. Matt is a member of the Washington Automotive Press Association and is a contributor to various print and online media sources.

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