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Chapter 4
– Air Conditioner Components
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Table of Contents-
Index1. Two-Cylinder Compressor
Many two-cylinder compressors are in use today. The Tecumseh has a cast
iron body and the York or CCI (Climate Control Inc.) is made of cast
aluminum. Both use reed valves mounted in a valve plate between the top
of the cylinders and the cylinder head. These in-line compressors may be
mounted horizontally, vertically or any angle in between. A pressure
differential of low pressure at the intake and high crankcase pressure—
along with centrifugal force from the rotating crankshaft—create lubrica-
tion pressure for oil circulation. The service fittings for charging or
evacuating the AC system are attached to the cylinder head of these
compressors.
2. Four-Cylinder Compressor
Four-cylinder radial compressors are produced by Tecumseh and
Harrison (GM). The cylinders are arranged inside a round housing in such
a way that they radiate from the center like the spokes of a wheel. The
pistons are moved in and out within the cylinders by a scotch yoke. A
scotch yoke is like a figure eight-shaped cam. The yoke pushes two
opposite pistons out to the top of their stroke and pulls the other two in to
the bottom of theirs. Each of the cylinders has it’s own reed valve plate.
The movement of the pistons circulates the refrigerant oil.
3. Five-Cylinder Compressor
The five-cylinder axial compressors made by Sanden and Zexel have five
cylinder bores, each fitted with a piston. The pistons are moved back and
forth by a rod that is attached to a rotating cam rotor by a ball and socket
joint. A reed valve plate mounts between the top of the cylinders and the
cylinder head. An inlet and a discharge port are mounted on the cylinder
head. The pressure differential between the inlet pressure and the pres-
sure inside the crankcase forces lubricating oil to all of the moving parts
in the system.
Note:
Seven cylinder compressors will be found on many
R-134a applications.
4. Six-Cylinder Compressor
Six-cylinder axial compressors are made and marketed by Zexel, GM
(Harrison Division), Ford, Chrysler and Nippondenso. All have three
cylinder bores, each fitted with double-acting pistons. The pistons have a
head on both ends. As they move back and forth inside the cylinder bores,
they cause each bore to act as two separate cylinders. The pistons are
moved by a swash plate that is mounted on the compressor shaft. These
compressors have two reed valve plates, one at the front and one at the
rear. Internal passages join the six cylinders so that refrigerant can flow
into and out of all cylinders through the one high and one low side service
fitting mounted on the rear of the compressor.