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Recharging your car’s A/C

Have you ever experienced windshield wipers that suddenly don’t work properly in a rainstorm? What about a tire that goes flat when you’re late for an appointment? If there were a special list for these types of vehicle shortcomings, your car’s air conditioning failing in hot weather would be near the top. Let’s learn how this happens and how to fix the air conditioning problem.

Car air conditioning dial

Car air conditioning basics and how-to tips

In the summer months, the process that cools and removes humidity from the air in a car is often used to its capacity. To run efficiently, it’s imperative that a car air conditioner has the proper level of refrigerant, its cooling agent. But if the car air conditioning isn’t working (if it’s not blowing cold air or there’s a clicking noise coming from the engine), then it’s likely that the unit needs to be recharged.

The great news is that you can recharge a car air conditioner by yourself. First, you’ll need safety goggles, gloves, charging hose assembly, A/C pressure gauge and R-134a refrigerant. To simplify things, you can now purchase recharge kits that include every component except for the goggles and gloves.

Here are the basics involved with getting the job done:

  1. Find the low-pressure service port under the hood. An "L" will likely mark a small plastic cap. Remove this cap.
  2. Start your car and put the A/C on its coldest setting.
  3. Attach the charging hose to the low-pressure port.
  4. Check the pressure gauge.
  5. Begin recharging the system with the refrigerant. You should periodically stop recharging to check the pressure gauge, which will help prevent overcharging the system.
  6. After recharging, you can replace the low-pressure cap. Note: Wear your goggles and gloves throughout this task, and carefully follow the instructions on your kit. Depending on the brand, there may be varying instructions.

Knowing your refrigerants

It’s important to know what refrigerant you need before starting any A/C-related task. For cars, that refrigerant is generally R-134a. However, depending on the type of A/C system, R-22 (often called Freon) can also be used. With new legislation on the horizon that will prohibit the use of the now legal and commonly used refrigerant R-22, it’s best to hire or at least seek the advice from a certified heating, ventilation and air conditioning (HVAC) technician. Certified HVAC technicians are knowledgeable; they know how to properly recharge air conditioners. They’re also aware of a commonly used, unsafe replacement product with a nearly identically name, R-22a.

According to the Environmental Protection Agency (EPA), R-22a can "catch fire or explode, resulting in injury and property damage" when used in air conditioners not designed to use propane. Since the name of the two refrigerants are nearly identical, consumers and HVAC technicians have again recently been warned by the EPA of the potential dangers. Using R-22a could also void a unit’s warranty. Beyond using the correct refrigerant, consumers must also be aware of several guidelines whether they hire a technician or choose to recharge their own vehicle.

According to the EPA:

  • A refrigerant must be approved by the EPA and can’t be intentionally released (vented) to the environment.
  • Technicians working on motor vehicle air conditioning systems (MVAC) must be certified under section 609 of the Clean Air Act (CAA), and they must use approved refrigerant handling equipment.
  • If an individual recharges their vehicle, the refrigerant must be properly recycled or reclaimed before it can be reused. It’s required even if the refrigerant is being returned to the vehicle from which it was removed.

A properly working air conditioner will not only make a vehicle’s occupants more comfortable, it’s also a good general maintenance task to tackle. Remember, it’s good practice to keep the receipts from any repair service. When it’s time to sell the vehicle, accurate maintenance records can increase the value of the car to potential buyers.

James Raia, editor/publisher at, is a freelance writer in Sacramento, California.
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