Every automobile parts store I walk in these days has freon for sale. When R-12 was around I was licensed to buy and use it. I thought that was a good thing because you can be severely injured and or do $$ of damage to the system your working on. I decided I would do this instructable for the following 2 reasons . First to help people to understand and be safe. Second to equip you to make a repair to your AC system if it just needs a Freon charge to bring it back to good working order. First a few Rules you need to always follow.
1. Since your car engine is running to charge the AC system there are moving belts and pulleys,fan(s) and very hot parts. You can easily loose your fingers if you put them where they don't belong!
2. Freon if sprayed as a liquid on your body parts will freeze them instantly- FROSTBITE
3.Don't release freon into the atmosphere. It is not good for the earth.
4.Wear safety goggles at all times incase a hose blows or something goes wrong and freon is sprayed on your face.
5. If after reading this instructable you feel unsure about doing this then you should not be doing it.
THIS CAN BE DANGEROUS AND THERE IS POTENTIAL FOR INJURY. I ASSUME NO LIABILITY FOR YOUR TRYING THIS. THIS IS JUST A DEMONSTRATION OF HOW TO DO IT. IF YOU DECIDE TO DO IT YOU DO SO AT YOUR OWN RISK.
Ok lets get started.
1. The adapter to connect from the freon can to your freon SUCTION SIDE of the AC system.
Found where you buy freon.
2. Freon- probably 2 cans if your system is barely cold. If it is cool but not as cold as it was buy 1 can
3. A thermometer
4. An AC system in need of some freon.
Step 1: Install the Hose on Can
We now make sure the pin in the tool is backed out so we cant see the point. We install the hose tool on the can. The can is not punctured. Once you screw the pin down into the can you can not remove the hose tool until the can is empty.When you screw the pin in to the can the pin seals in the freon. The other end of the hose also has a safety seat built in it so if the pin is backed out it will not vent freon to the atmosphere.
AS LONG AS THE CAN IS UPRIGHT ONLY VAPOR COMES OUT OF THE HOSE
IF THE CAN IS UPSIDE DOWN LIQUID COMES OUT SO KEEP IT RIGHT SIDE UP!
I spent a lot of time on this simple step but that was so you do this SAFELY.
Step 2: Familiarization With Your Cars Freon System.
First see what freon your vehicle uses. There should be a tag on the radiator cover cowl or somewhere under the hood that tells you. Look for 134A. If it says 12 this Instructable does not apply to you. There are conversion kits but that is beyond the scope of this demonstration. Now check out the pictures to see what the basic parts of an AC system are. Note that there are parts you can't see and we won't address those as they are not necessary to know about to charge the system .
The basic AC system has a pump or compressor that pumps a low pressure gas
Once it travels into the evaporator it is now a low pressure cold gas again and not a liquid. It then leaves the evaporator and goes through hoses to the accumulator / drier which is just a big tank to catch any liquid that might of snuck out with the gas. Then from there the low pressure cold gas goes back into the compressor to start the cycle all over again. You may of noticed the system has a high pressure side and a low pressure side-VERY IMPORTANT. You will only work on the LOW PRESSURE SIDE. The freon is added on the LOW PRESSURE SIDE ONLY. The hose tool you bought is made so you can only hook to the low side as the high side and low side fittings are different sizes and shapes for SAFETY'S SAKE.
Step 3: Hooking Up the Freon
Remove the SUCTION SIDE port cap. This can be in a number of places on your car so you may need to look for it. It will always be on a bigger tube. By that I mean the high pressure side tubing is smaller diameter than the low pressure side. Thankfully the ports are not interchangeable so you can't plug on the wrong port. The air in the line is vented now by loosening the fitting (see pictures)
Then retightend and The can punctured by screwing in the pin until it bottoms.
Now start the car and turn the AC or climate control to high and the fan on high.
Make sure the temperature control is at full cold or set it to the lowest temp you can if it has numbers.
Now we are ready to charge the system.
Step 4: Charging the System
You now start the car with the AC system on high. You open the can tap so freon starts to travel from the can to the suction side. You only need to open the can tap 3 to 4 turns and you will feel the top of the tool getting cooler. This tells you the can is open enough. Don't try to unscrew it all the way to make it go faster as the needle can be screwed out of the can tool and then you have a fountain of freeze spraying all over- not good. Freon moves from the can to the suction side because the can is under low pressure but the suction side is under even lower pressure so the freon leaves the can and moves to the system. Now watch the accumulator can. If you can safely touch it you will see it's warm if your low on freon. As you charge the system it will become cooler. Finally it will start to sweat. That is when you stopAdding freon. Now you have about the right amount. If you add too much your over stressing the system and it is not going to work any better in fact it will not be as efficient. Overcharging also adds stress to the system since pressures are higher than normal. So now that the accumulator is sweating close the can tap. Check the temp in the car and you should feel very cool air . I dropped from 87 to 50 degrees with a can and 1/2 of another. The cans come in preset quantities. I don't ever buy the large completely charge your system can as it is usually too much. The smaller cans are what you need. I don't recommend the sealer in a can. If you think you need to add oil to your system take it to a shop so its done correctly. Any left over freon do not vent to the atmosphere. tighten down the can tap and leave the tool on the can. You can tell when a can is empty as if you shake it it will feel empty.
Close the tap before you remove the hose off of the fitting. Then recap the fitting. If your system does not work properly ( no cold air ) it is time to go to a pro. Open freon can be used at a later date but must be stored in a cool place That is CHILDPROOF. The temperature coming out of your vent can vary depending on a lot of factors so don't think you have to see the temperatures I saw.
Step 5: Final Thoughts
As you can see in the photos we dropped 30 degrees and it actually went down to 51 degrees. Good enough.
SAFETY GLASSES AND IF YOU WANT GLOVES...
Charge the system with the can upright position. By the way it can take up to 1/2 hour to charge a system...
If your system is very low when you start putting in freon the compressor may not start turning until a sensor sees you have a predefined minimum amount of freon. Add 15 minutes more for charging. This is a safety so you don't damage the freon compressor...
If you see oily goo all over your compressor or at a line fitting don't bother charging it as it needs pro service or your shooting your wallet in the foot in the long run...
If after you charge your system the cold air comes and goes and comes and goes you have moisture in the system and it needs to go to a pro...
If things don't seem to be working as I have described in this topic then something else is wrong and you need to have a trained pro look at it...
Remember a pro uses gauges to check pressures on the high and low pressure sides. He factors in ambient air temp and even humidity levels and he can pinpoint complex problems like that. We used the >watch the symptoms< process to determine we are in the ball park in terms of the amount of freon we have in our system. My feeling is a little low is way better than too much...
After your all done check the port cap to see its in place. Put your tools away. Go for a nice cool ride. If it all works ok go look in the mirror and say. I DID IT AND PAT YOUR SELF ON THE BACK FOR A JOB WELL DONE!