Adding freon to my central air

Did you try to add freon because is was no longer blowing cold air? Who added the freon local repair shop or A/C specialist?

Possible bad fitting wher lines connect.

Is the compressor starting? On the outdoor unit you will see a large copper pipe and a small copper pipe. Is the larger of the two cold to the touch? wet? Just because a central air system is not blowing cool air does not mean it needs freon. If you have clogged filters it cannot do an air exchange. So, I would recommend checking the easiest things first before adding Freon.Most people make the mistake of adding Freon and overcharge their system. In a low load situation you can slug the compressor with liquid and your system is ruined. If you do have to add Freon it indicates that you have a leak. An AC System is a closed system and if it is working properly you should not have to add Freon.

internet heat/cool supply houses sell piericing valves attach to large line called suction line screw the valve in then back off a few turns add freon usually r134a avail. at auto parts stores in 1 pound cans

If its R22 you have to have a license to buy it. But outside unit on the larger copper line will be an access will look like a 3/8 copper fitting with a cap on it there is also one on the small line. You will need a tank of r22 and a set of gauges. If the compressor is running you add freon til the large copper line starts to sweat. The small line (high side) should not slug or have the gage on it jump this means its overful or has air contamination in it. Always add thru the larger line.good luck

Find the access ports. The large line is the Low side and that is where you will add freon. The small line is the high side and don't ever add freon through it.

Large pipe

Yes you can add freon, the port will be on the line up at the accumlator tank (large silver tank on pass side close to the fire wall - will have a large black cap, does not look like a port) Get you a large can with a hose attached do not use it all save some for next year. 

Adding refrigerant (Freon is Dupont's name for refrigerant) requires some special tools and gauges. More important than that is your system should not loose refrigerant. It you are low that means you have a leak in the system. It should be found and repaired before new refrigerant is added. A qualified repair technician should be called.
Sincerely,
Terry aka Funny Plumber

add freon to low pressure side . low pressure side is large line with small fitting. high pressure line has a large fitting.