Car Care - Adding Refrigerant to You A/C System


An effectively operating air-conditioning system is not only a comfort factor - it can be a matter of health, especially for the sick, the very young and the elderly. For the benefit of both you and your passengers, make sure your system operates correctly and efficiently.

Follow instructions in your vehicle-specific repair manual and check your air-conditioning system periodically. If your air-conditioning system is not providing enough cool air, you can add refrigerant yourself and save time and money.

Note: The following are general instructions. Always refer to a repair manual written specifically for your car, truck, van or SUV when performing any type of maintenance work.

Buy an automotive a/c charging kit at an auto supply store. This kit includes a 14-ounce can of refrigerant, a tap valve, and a short section of hose for attachment between the tap valve and the system's low-side service valve. One can of refrigerant may not be enough to bring the system charge up to the proper operating level, so it is best to purchase an additional can. Be sure one of the cans contains red refrigerant dye. You will be using this dye to help you locate any leaks in the system.

Caution: Two types of refrigerant are used in automotive a/c systems: R-12, which was used widely in older vehicles, and R134a, which is safer for the environment and is used in newer vehicles. These two types of refrigerants (and their corresponding refrigerant oils) are not compatible. They must never be mixed; otherwise components could be damaged.

Follow the manufacturer's instructions and hook up the charging kit. Warning: The fittings on the charging kit are designed to be used only on the low side of the system. Do not hook up the charging kit to the system high side.

Warning: Wear eye protection when working with pressurized refrigerant cans.

Making sure that first the rubber seal or O-ring inside the threaded portion is in place, back off the valve handle on the charging kit and screw the kit onto the refrigerant can.

Remove the dust cap from the low-side charging connection and attach the quick-connect fitting on the kit hose.

Warm up the engine. Turn on the air conditioner. Caution: Keep the charging kit away from the fan and other moving parts.

Turn the valve handle on the kit until the stem pierces the can. Back the handle out to release the refrigerant. Listen for the sound of the gas. Add refrigerant to the low side of the system until the compressor inlet pipe feels cool to the touch and the discharge line feels warm. Allow stabilization between each addition.

Place a thermometer in the center of an air vent inside the vehicle. Note the temperature. A fully-charged system that is working properly will cool the air at the vent down to about 40 degrees Fahrenheit. This is generally 30 to 40 degrees cooler than the outside air.

When the can is empty, close the valve and release the connection. Replace the dust cap on the low-side port.

Warning: Do not add more than two cans of refrigerant to the system.

Remove the charging kit from the can. Store the kit with the piercing valve in the UP position. This will prevent inadvertently piercing the can on the next use.