Rubber, automotive air-conditioning refrigerant hoses are assembled with special fittings, made of steel. The end connection, shape and angle of the fitting can be individually designed to match the make or model of a car. The typical types of connections in automotive A/C systems:

• fitting with UNF imperial thread nut, with 45° cone (SAE type) pipe;
• compressor fitting with 1″-14 UNF imperial female thread nut;
• O-ring sealed pipe fitting with UNF imperial male thread nut;
• fitting with a socket, with UNF imperial male thread;
• fitting with UNF female thread nut, type ORFS;

There are many other types of fitting. Hose connectors are often used, and sometimes adapters and quick release couplings. The fittings of large sizes (for buses) are made to different standards (flanges, metric threads).

Solder nipples are ideal for A/C repairs. A worn hose can be replaced and the nipple soldered to the end connection of the original fitting.
The fittings are straight and angled. They can be equipped with a built-in refrigerant charging valve.

The fittings are mounted to the rubber refrigerant hoses in several different ways:

• fast assembly system – a fitting with a hose tail of special shape, assembled with clips using special pliers; clip holders are used to set the position of clips; the system is mainly intended for service and repair;
• crimped with ferrules – a beadlock fitting consists of a sheet metal ferrule integrated with the fitting, crimped with special profile dies in crimping machines – the system is used primarily in series production;
• reusable – ferrules are screwed onto the hose, then the fitting is screwed into the hose and the ferrule – the system rarely used today.

When selecting a fitting, it is important to determine the type and size of the connection, the inner and outer diameter of the hose (is it a traditional, thick or maybe a thin refrigerant hose).