Replacing Freon in an Air Conditioner

Accessing the A/C compressor under the hood.
What You'll Need
Owner's manual
Replacement Freon
What You'll Need
Owner's manual
Replacement Freon

If the air conditioner in your car is no longer blowing cold air, it may be time to recharge it with replacement Freon. Freon is the chemical refrigerant used in air conditioners to cool the air pumped through the system, and it always runs out eventually. Replacing it yourself can save a lot of money you would otherwise pay to an auto mechanic.

A/C Basics

The way in which an air conditioning unit works is rather complicated, but simply put, hot air is pulled from the inside of the car and expelled to the outside of the car. Air is then pulled through the car’s system, cooled, and then pushed into the car's interior through the vents.

Cars made prior to 1993 use R12 Freon, an environmentally damaging product that is no longer available to the general public, but can be acquired and used by professional mechanics who have access to the required environmental waste disposal process. Cars made after 1993 use R134a Freon, which is readily available at auto repair supply retailers.

Note that R12 and R134a refrigerants do not mix so do not attempt to recharge a car that has a pre-1993 air conditioning system with R134a Freon. If you have a car that was manufactured prior to 1993 and are having problems with the air conditioner, it is best to take it to a professional mechanic to diagnose the problem and have the system recharged correctly.

With the right supplies and a little instruction, replacing A/C Freon is an easy do-it-yourself project.

Step 1 - Attach Freon Can to Compressor

Using your owner's manual, locate the hoses to the air conditioning compressor in your car. Attach the shorter hose to the can of replacement refrigerant, but do not completely tighten the connector.

Step 2 - Open the Can

Open the valve on the Freon can to release air from the system, and tighten the connection and valve.

Step 3 - Draw the Freon into the System

Start the engine and turn the A/C on high. Holding the Freon can upright, slowly open the valve on the short-end manifold. When the can appears to be close to empty, slowly close the valve again and then carefully remove the can from the hose.

Step 4 - Add More Freon

If this is your first time adding refrigerant to your car, you might want to work in small steps, repeat steps one through four as needed until system is recharged. Otherwise, simply aim to recharge the system fully the first time through.

If you’re confident your A/C was recharged fully and you continue to have problems with getting cool air from your vents, you may have other issues or a refrigerant leak. In any case, it would be best to see a mechanic for repairs.