Air Conditioning and Coolant
Ford Ranger XLT
Heating Ventilating and Air Conditioning

How do you add freon to your air conditioner?

User Avatar
Wiki User
May 05, 2015 2:41PM

You need EPA certification to purchase and use any refrigerant that has an Ozone Depletion Potential (ODP*) greater than zero. These would include any refrigerants containing chlorine compounds such as R12 (CFC12 - formerly used in cars and trucks) or R22 (HCFC22 - no longer used in new central or window A/C units, but still in use in most existing units). Many other refrigerants also contain chlorine compounds, but these two are the ones you will find in most older home or automotive equipment.

The problem with chlorinated refrigerants is that once they enter the atmosphere and are broken down by solar action, the chlorine molecules break free and can eventually damage the earth's ozone layer. The ozone layer is "way up there" and serves to block the most harmful solar radiation which causes skin cancer, etc. Although that's a very basic and simplified explanation, it works well enough for our purposes here. For these reasons, and up to this point, the above quoted answer is partially correct.

However, not all refrigerants contain chlorine, and those that don't contain chlorine have zero ODP*. Two examples would be R134A, used by most vehicle manufacturers, and R410A (one trade name is "Puron") now used by most residential A/C manufacturers. If you do some digging on the EPA web site, you will find that sales and use of R134A and R410A and a few other refrigerants are not currently restricted by the EPA, and it is legal for anyone to purchase them if the state they're in allows it. (You must also be aware of any state and local regulations.)

You should also know that your equipment may not need more refrigerant - the problem may have a different cause - and you can't just add any kind of refrigerant, since equipment is designed to use only certain refrigerants and oils. Adding the wrong ones can do serious damage to the compressor and other expensive components.

As for adding refrigerant to your own equipment: in most cases, it's not a good idea unless you have the tools, training, and experience for the job. There are risks to your personal safety, risks to the equipment if serviced improperly, and risks to the environment if refrigerant is allowed to escape. Also, regarding the environmental risks, the EPA makes it absolutely positively crystal clear that it is illegal to deliberately release ANY refrigerant, even non-chlorinated refrigerants, into the atmosphere. All refrigerants also have a global warming potential (GWP), so that is also an environmental consideration.

As mentioned earlier, you may check the EPA web sites to verify this information, and also to keep up-to-date on the latest regulations.

Window air conditioners are not designed to allow adding Freon. They are charged at the factory and hermetically sealed, so they shouldn't have any leaks or require recharging for the service life of the unit. If a window air conditioner no longer cools adequately it is most likely due to dust buildup on the coils, or eventually, the compressor wearing out and and becoming inefficient. If the unit has been used extensively, but otherwise maintained, the compressor may be suspect if the unit is over 10 years old.

Central air conditioning units have fittings on them with Schrader valves, similar to those found on automotive air conditioning systems. There is a high pressure side valve and a low pressure side valve. Refrigerant is added on the low pressure side, preferably while the compressor is running. A technician will use a special gauge manifold that allows monitoring of high side and low side pressure simultaneously while adding refrigerant from a portable cylinder.

Current regulations require an HVAC license to purchase and use refrigerants such as R12, R22 and R134a, generally called "Freon", although technically, not all refrigerants are sold under that brand name. There are alternatives, such as Duracool, which can be freely used in systems originally designed for R12, R22 or R134a, without having to change seals or lubricants, and can be purchased and handled without an HVAC license. Duracool-type refrigerants are essentially highly refined propane, and are thus flammable, so they need to be handled with care. Otherwise, they are environmentally friendly and non-toxic.

Try cleaning your coils first, not just the outside. Most service techs never clean the (evaporator) that's above your furnace because it is tough to do. Clean first before you assume anything. One reason it may be dirty is if you have indoor pets.

You can add freon to the low side of your a/c. When the gauges are attached to the system, you can use the third hose to attach to the freon can. Make sure you leave the can upright so as to add only the gas. Don't turn the freon can upside down to add liquid as this can lock up the compressor and then you will have to call the a/c repairman.

More information:

First, you need to be EPA certified unless you are charging your own appliance, and if adding certain types of refrigerants, certification is required to purchase the refrigerant as explained above. You need to know what kind of refrigerant. [ R22 R143a etc. ] On a home system a good set of gauges and connect properly on a 22 unit low side is blue, suction line is larger in size pipe. High side red smaller diameter. Connect both hoses check pressures if their is no reading the compressor is not running. If compressor is running on a 22 unit the high side red should be 225 to 275 should not go above 350 psi or it will cause damage your unit more or cause a rupture low side should be from 60 psi to 80 psi don't go any higher to much freon is no good and will cause higher temp. Be careful because were talking high pressures you should have a certified tech. do this if you add freon you must have a leak it dose not evaporate their is no winter summer freon its a sealed system and should never need refrigerant.

Some things to know:

#1. Don't burn your fingers, it hurts, real bad.

#2. Don't overcharge, even a little too much and you wont' remove humidity and it will never cool.

#3. He didn't mention bleeding out the air from your lines before charging after hooking up the cylinder, let that air into your system and you are causing more trouble.

If you want to do typical home improvement type things, if you are a DIY guy, stick with changing your filter monthly, make sure your drains are clear, and change/ check your thermostat batteries. anything else you are playing with high voltage, and freon.

I have had plenty of customers that decided to change their thermostat themselves to save $50. They shorted out the board, ended up costing themselves a $500 repair.

I would listen to the advice freezer-burn hurts an makes your finger black, and did you need to add refrigerant or take some out? Remember also to reclaim the refrigerant in an" EPA "approved cylinder. If you over load your compressor it will fail. If the compressor burns out it may have a chemical reaction with the refrigerant and produce acid in your system. Now you have a real mess at that point! All the refrigerant has to be removed, the compressor / motor replaced, the system purged, the oil replaced the refrigerant replaced, a run up of the system to check that it is running properly. I believe I would leave the servicing to the technician who has extensive (hours of class room and field experience) training.

Check cooling coil/evaporator(in the door unit)if there is ice built up then feel the air vent. If you do not feel air, it means your vent is blocked and you may need to clean the air vent. You probably have a leak. You need r22 test gauge and hose, reamer, tube cutter and flaring kit.

Check the suction pressure (big tube at out door unit) and remove 2 way cap and 3 way cap valve then connect the blue hose at service port 3 way valve (port located at left or right depends on the manufacturer.) You will get pressure about 40-45 psi (air conditioner is running) then use an Allen key(hexagonal wrench) to close 2 way valve (small tube or gas discharge side) wait 1-2 minute cooling operation then close 3 way valve (suction tube or big tube) immediately shut off air conditioner and pull out power chord. You may need 2 people one at in door unit and the other at out door unit. This method is to keep remaining gas inside the compressor/condenser. Then leak check, open 2 way valve about 90 degrees hold it for 10 seconds then close it. Measure the pressure and keep it open for 5-10 minutes. If the pressure does not indicate the same as when it was first measure it means that you have a leakage. For air conditioners 1- 5 years old, the leakage will happen at the copper tubing connection and improper flaring. Then you will need to clean the in-door and out-door unit. Use a spanner or wrench to loosen the copper flare nut at the out-door unit and in-door unit (inside insulation) then use PVC tape to cover all copper pipes to prevent dirt from going inside. Lift up out-door unit and use coil cleaner detergent. Wait 5 minutes then flush with water. Remove indoor front panel then disconnect out-door unit cable at front panel in door unit. Lift up indoor unit to disengage the hook and pull out the indoor unit, then clean the cooling coil, cover electrical parts with plastic. The last step is that you need to cut (use cooper cutters) the copper pipe on the flare nut connection (low side with big tube and high side with small tube) in-door connection and out-door connection. Then you will need to remove the burr from cut edge using reamer and make sure metal powder does not go in. Make a flare after inserting the flare nut onto the copper pipes. You can install the unit back now. Check the low side pressure of the unit. If the pressure is between 55-67 psi no need to charge it. Before u charge r22 gas u need to to purge air inside piping/tubing by using leakage check method. Just use the service port so their will be no need to use test gauge. Crack open 2 way valve for 10 seconds then close it. Now push the pin(same as a tire pin) at the service port 3 way valve for 3 seconds repeat this three times. You may need to purge all air inside test gauge and hose. Then check gas leakage using same method that was already explained. CHECK suction pressure 55-67 psi in running mode and set it to the lowest temperature (16 Celsius/27 Fahrenheit) and pipe length below 10 feet should be okay. If it is not okay, you will need r22 gas tank. Connect yellow hose to r22 tank and middle connection at test gauge. Then fully open tank valve and crack open blue stem at test gauge (do not exceed 60 psi to prevent flooding the compresser) for 30 seconds to 1 minute then close it. Measure the pressure for 1-3 minutes. Repeat this step until you get 67 psi in running air-conditioner or u can feel the suction pipe to see if it is cool. If your unit already empty you need r22 lubrication and weight scale put r22 gas-tank on the scale and read at out-door unit tag how much the manufacturer recommends the weight should be. Then u need to fill the yellow hose with r22 lubrication about 5-10 milliliters. Repeat charging method that has already been explained and measure the weight of the gas according to the manufacturer and then you are done.

What is "Super heat"?

You will hear and see this term all the time in reference to refrigeration. Simply put it is the difference between the temperature of a vapor line in relation to the temperature scale on a pressure gauge for a particular refrigerant or how much liquid is feeding the evaporator in relation to how fast it is being boiled off. for example (R22) if the suction gauge reads 70 psi then the evaporating temperature is 41 degrees but if the tubing is 51 degrees then you have 10 degrees of Superheat. A typical range for residential air conditioning is 8-18 degrees with some error based on extreme conditions. Once you understand Superheat you can diagnose obvious problems. For example a system that is under charged or has a stuck (closed) metering device will have high super heat (over 20 degrees) at the compressor and a system that is grossly overcharged or has a dirty indoor coil will have very low Superheat about 3-7 degrees with low suction pressure and the suction line will be very cold. It is ok and quite normal for the Superheat to change dynamically while the system is running, you will have to interpret what you are seeing.

What is "Sub cooling"?

Sub-cooling is similar to Superheat but happens in the condensing portion. Refrigerant when condensing will happen at a particular temperature which is very close to the temperature scale corresponding to head pressure for a given refrigerant. After the refrigerant is condensed it will try to assume ambient temperature but will never reach it. The difference between liquid line temperature and condensing saturation temperature is Sub-cooling and is a very good indication of "refrigerant level", but only when proper Superheat is indicated or you could have a misleading indication. Typically 20 degrees of Sub-cooling is desirable and the closer the liquid line temperature is to ambient the better (indicating an efficient system). Checking Sub-cooling in the heat mode of a heat pump has to be done carefully because you have influence of the space between the indoor coil and the point of measurement. For best heating you will want most of the refrigerant to be condensing in indoor coil without backing it up with refrigerant.

As a general rule Sub-cooling = Refrigerant charge quantity, Superheat = Refrigerant cycle performance. Check both!!!