Compressor Oil; Moisture In The A/C System - Mazda CT-L1005 Training Manual

Basic Climate Control

Compressor Oil

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The compressor oil in the A/C circuit is required to lubricate the moving parts of the
compressor. The oil is carried throughout the system by the refrigerant. The compressor
oil is highly hygroscopic PAG (Poly-Alkaline Glycol), meaning it easily absorbs moisture
(much like brake fluid does).
NOTE: Older Mazda vehicles with R12 refrigerant use mineral compressor oil, which must
not be used anymore. In addition, mineral oil and PAG oil must not be mixed.
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The current range of Mazda vehicles all use PAG oils, but there are several different
types available. They can have differing characteristics such as different viscosity. For
this reason, the different compressor oils are not interchangeable. This means that when
servicing a vehicle, the correct oil needs to be put into the A/C system.
NOTE: Compressor oil needs to be properly disposed of just like any other environmentally
harmful fluids (brake fluid, engine coolant, etc.). Consult the local authorities to find
out if there are special requirements for discarding the oil in your country.

Moisture in the A/C System

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Water in the closed A/C system is an undesired substance, because it causes corrosion
on the system components. The only way that water should be able to enter the system
is being transported as moisture in the air. When a system still has refrigerant in it, there
is pressure, and there is no way for moisture to enter the system. When a system is
opened, and the refrigerant is removed (during service), or the system is open to the
atmosphere (as a result of an accident), then it is possible that air enters the system. In
the air is moisture, and this moisture can be trapped in the system.
Curriculum Training
Fundamentals
02-13