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How to Diagnose Car A/C Problems & Charge the Unit | NAPA

A/C controls on a car

Warm Weather Driving is a Breeze Until it Isn’t

When it’s warm outside, driving becomes one of life’s true pleasures. You’re cruising down the road with the windows down, music playing and a cool breeze blowing. Eventually, the mercury rises and it’s time to roll up the windows, close the sunroof and crank up the air conditioning. But if you find that you only feel warm air coming out of your vents after a few minutes, your A/C system could have an issue. 

From a 2015 Volvo s60 to a 2009 Acura 3.2 TL, it can be intimidating to diagnose air conditioning problems in your car. These systems operate much like the cooling system of your engine. The evaporator pulls hot ambient air over a series of coils that contain a refrigerant (usually R-134a). The heat is absorbed and chemically transforms the refrigerant from a liquid to a gas. The gas enters the compressor and pressurizes the chemical before finally passing it into a condenser, which returns the chemical to liquid form while dissipating heat. That process repeats and eventually the hot, humid air in your cabin is replaced by cool, refreshing air. It gradually removes the warmth and humidity from your vehicle’s cabin and replaces it with cool air that is emitted from the vents.

Because you’re air conditioning system is one of the most complex and labor-intensive repair projects you’ll find in your car, truck or SUV, it’s important to get an understanding of its parts so you can better diagnose the issues. Let NAPA AUTO PARTS guide you through how to fix the A/C in your car so that you can stay cool while you drive this summer. 

How to Diagnose A/C Problems in Your Car

When performing car A/C diagnostics, first thing’s first: you should check the different components of the system to ensure they are not visibly damaged or broken. 

  1. Condenser Check: Your vehicle’s air conditioning condenser looks like a smaller, thinner radiator and is usually located under the hood towards the front of the car near the radiator itself. Check to see if the condenser fans are fully operational while your engine and A/C is running. 
  2. Compressor Check: Normally located near the rest of the belt-driven components under your hood, the air conditioning compressor is responsible for keeping the compressed refrigerant circulating through the system. Non-electric vehicles use belt-driven compressors, and over time, the belt can wear down, crack or even break altogether. So, check the integrity of your A/C compressor and compressor belt.
  3. Fuse or Relay Check: Some compressors that are belt-driven use fuses and relays, so refer to your owner’s manual, locate the correct fuse and test it to see if it’s faulty. NAPA AUTO PARTS carries a wide range of fuses and relays for vehicles old and new.

If these components are intact, then a great option for the DIYer is shopping NAPA AUTO PARTS for an A/C Manifold Gauge Set. These gauge sets are designed to test the air conditioning system to see if it’s fully charged and help determine if there is a leak. They can also fully evacuate your system prior to any repairs (this should only be done using a refrigerant reclamation system or by a professional shop equipped with a reclamation system as venting refrigerant into the atmosphere is illegal). Locating and troubleshooting a leak in the system may seem difficult, but an A/C Leak Detector and a little NAPA Know How goes a long way. Soon you’ll be detecting leaks like a NAPA technician.

Once you’ve determined that your air conditioning needs a recharge, visit your local NAPA AUTO PARTS to pick up an A/C recharge kit. It’s the easiest way to get the cold air blowing in your car or truck again. While you’re there, make sure to pick up some safety essentials, such as goggles, gloves and shop rags. You should always use goggles and gloves when checking the A/C charge in a car or when doing an A/C recharge. Unexpected refrigerant exposure on the skin and eyes can cause frostbite. Always be sure to carefully read and follow the instructions on your A/C recharge kit.

How to Charge the A/C in Your Car

  1. Put on your protective gloves and eyewear.
  2. Using a temperature gauge or thermometer, determine the outdoor temperature.
  3. Adjust the recharge kit gauge so that it matches the outdoor temperature. You can target the correct temperature and PSI with the arrow on the gauge. So, if the outdoor temperature is 80 degrees Fahrenheit, the gauge would indicate 45 PSI.
  4. Start your car and connect the temperature gauge to one of your A/C vents. 
  5. Set the A/C to the coldest setting.
  6. Connect the hose to the kit and shake the can. Then, screw the adapter on the end of the canister’s hose into the A/C’s low-pressure service port. You can find this by locating the Schrader valve that usually has a cap with an “L” on it for “Low.” (Note that this is the only port where the adapter will connect.) 
  7. Follow the instructions on your A/C recharge kit. Squeeze the trigger and tilt the bottle back and forth. After ten seconds, check the readout to prevent overcharging. 
  8. Resume the process until you’ve obtained the correct amount of pressure. Disconnect the kit and reattach the cap to the low-pressure port.

Make sure to check NAPA Online for all your automotive air conditioning repair needs like A/C parts and A/C system service and repair kits. Keep in mind that fixing the A/C in a car can consist of repairs that range in difficulty from easy to extremely complex and time consuming. Additionally, you can always trust the friendly technicians at one of our 17,000 NAPA AutoCare locations for reliable A/C repair work. We’ll make sure you get back on the road with ice cold air blowing in no time! 

Photo courtesy of Pixabay.

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More than 90 years ago, the National Automotive Parts Association ("NAPA") was created to meet America’s growing need for an effective auto parts distribution system. Today, 91% of do-it-yourself customers recognize the NAPA brand name. We have over 6,000 NAPA Auto Parts Stores nationwide serving all 50 states with a unique inventory control system that helps you find the exact part that you need.

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