Although it is possible to buy cans of refrigerant from aftermarket parts suppliers, it’s not a good idea to try to go it alone trying to charge the complex air conditioning system in todays vehicle. There are lots of ways to save ways on auto repairs, but this is not a good way.
The air conditioning system in your car is extremely sophisticated, trying to repair it on your own could cause hundreds of dollars in damage to your vehicle, not to mention the damage it will do to your pride when you have to have the vehicle towed to a garage to be repaired after your failed attempt at.
The system is designed to hold a precise amount or refrigerant, if you are off by one or two ounces either way, it may not function correctly, and if you overcharge it by even two ounces, you risk damaging the compressor. An overcharged system can cause the compressor to lock up, which in some cases will mean that the vehicle will not run. Without the correct tool to evacuate the system, you have no idea if there is any Freon still in the system, so you have no way of knowing exactly how much to add.
You are always better off when it comes to air conditioning to take your vehicle to a mechanic certified in air conditioning. He will be able to tell you how low your system is, evacuate the system, check it for contaminants, recharge it with the correct amount of refrigerant and check for any leaks. If your system is low on Freon, it had to have gone somewhere, it doesn’t evaporate. Your mechanic will also be able to tell you if your system is completely empty. If that is the case, you should have the accumulator (also referred to as a receiver dryer depending on where it is located) replaced. It contains a desiccant, which absorbs a finite amount of moisture from the system. If the system has a leak and has been contaminated by moisture, that accumulator will no longer be effective at it’s job of keeping moisture out of the system and will need to be replaced.
With all that said, if you are still sold on adding Freon on your own, you will need to do the following:
1. Do your research. Identify the type and total amount of refrigerant the system should have, you need to make sure that you do not add more then that. Most vehicles made after 1996 use R134, older vehicles use R12
2. Make sure the system is running. Start the car and allow it to run for a few minutes with the air conditioning on.
3. Find your fitting. Identify the low side fitting (if the system has R134, it’s the larger of the two fittings, if it has R12: it’s the smaller of the two fittings).
4. Add your Freon. Add Freon slowly with the system still running until you start to get condensation on the line to the compressor. Some vehicles, although very few, have a sight glass that will allow you to add freon with the system running, keeping an eye on that sight glass, when the bubbles disappear, you can stop adding.
