R-12 is the coldest
the point where refrigerant evaporates in the evaporator. Generally the center of the evaporator.
That depends on what kind of AC system it is (e.g., home, commercial, automotive) and when it was manufactured.
Well, we'd need to know what make, year, and model of car before that question can be answered. Not all automotive AC systems require the same amount of refrigerant.
Take it to a professional. If you are asking in this forum you do not have the equipment or skills necessary to work on an automotive refrigerant system.
The first thing to check... refrigerant pressure. It's almost ALWAYS the refrigerant. The design of an automotive refrigeration A/C system isl not quite the same as your kitchen refrigerator, which almost NEVER leaks refrigerant. The hoses and compressor seal on your automotive AC leak. It may be a very slow leak, but they ALL leak, so before you put a lot of money into speculation, check the pressures on the AC system and if it's low, add refrigerant. Having said that, it CAN be a failed compressor clutch, downright worn out compressor, bad fuse or worn out switch. ... but start with the refrigerant.
The proper term is actually refrigerant - Freon is a specific brand name trademarked by DuPont for a series of CFC and HFC refrigerants - thus, an AC system only has Freon if it has the product manufactured by DuPont. Answering your question, yes, an outside AC unit uses refrigerant, although it's normally not the same type used in automotive AC systems.
R134A is the only approved refrigerant for automotive use.
No. First off, the trustworthiness of any such kit sold at Walmart is questionable. Secondly, the kits are intended for automotive AC systems, and will come with R134a refrigerant... window units use a different type of refrigerant (often R22, from my understanding). Different refrigerants cannot be blended, and doing so will ultimately damage the AC unit.
If you are referring to automotive refrigerant, the answer is no. Neither refrigerant will work properly if mixed and might damage the compressor or other components.
What Ac refrigerant freon is required in 1989 BMW 7-Series? What Ac refrigerant freon is required in 1989 BMW 7-Series?
134a refrigerant
Many home AC units are sealed, and there is no way for a homeowner to add refrigerant.