G
CAUTIONARY POINTS FOR MAINTENANCE
REFRIGERANT™134a (R-134a)
Outline
• R-12 and other fluorocarbons now used in air conditioners can destroy the ozone layer in the strato
sphere. The result is an increase in hazardous ultraviolet rays which over time can adversely affect
both human health and the biosphere. Because of this concern, Mazda has chosen to use R-134a
(HFC-134a), a hydrofluorocarbon-based refrigerant that does not deplete the ozone layer, in this
vehicle.
• R-12 and R-134a are not interchangeable; system parts and system service tools also differ. The
table below compares the two systems.
Refrigerant systems
Part
R-12 system
Refrigerant
C hlorofluorocarbon-12
(CFC-12)
2
2
[CCI
F
Compressor oil
Mineral oil
O-ring
Nitrile butadiene rubber
(NBR)
Fluorine rubber
Joint nuts
Inch threads
Joint blocks
Charging valve
Screw-on type
Hi: 3/8 -24 UNF
Lo: 7/16-20 UNF
G— 4
CAUTIONARY POINTS FOR MAINTENANCE
R-134a system
Hydrofluorocarbon-134a
(HFC-134a)
2
]
[CH
FCF
Polyalkylene glycol oil
(PAG oil)
High-circulated nitrile
butadiene rubber
(HNBR)
Metric threads
—
Quick-connect type
Hi: 16mm {0.6 in} dia.
Lo: 13mm {0.5 in} dia.
If the refrigerants are mixed or one refrigerant is
used in a system that requires the other, the
3
compressor oil will separate from the refrigerant
]
and not circulate within the system. This can
damage the A/C compressor and cause abnor
mal compressor vane noise.
In addition, mixing R -134a with R -12 or using
R -134a instead of R -12 in an R -12 system can
lower the durability of the NBR O-ring and dis
solve the fluorine O-rings. If the fluorine O-rings
are dissolved, refrigerant may leak.
Special compressor oils for R -134a air condition
ing systems are developed by each air condition
ing vendor. Therefore, use only the specified oil
for each model vehicle. If a PAG oil other than
specified type is used, the A/C compressor and
refrigerant system can be damaged.
If the oils are mixed or one oil is used in a sys
tem that requires the other, the refrigerant will
separate from the compressor oil and not circu
late within the system. This can damage the A/C
compressor and cause abnormal compressor
vane noise.
Mixing PAG oil with mineral oil or using PAG oil
instead of mineral oil in an R -12 system can
lower the durability of the NBR and fluorine rub
ber O-rings.
If an NBR O-ring is used in an R -134a system,
the PAG oil and R -134a will lower the durability
of the O-ring. If a fluorine rubber O-ring is used
in an R -134a system, the R -134a will dissolve
the O-ring and cause the refrigerant to leak.
Thread standards for joint nuts connecting pipes
and hoses have been changed to avoid con
necting R -12 system parts with R -134a system
parts.
The bolt sizes and part measurements for joint
blocks connecting cooler pipes and cooler hoses
—
have been changed to avoid connecting R -12
system parts with R -134a system parts.
The shape of the charging valve differs for each
system to avoid confusion. The quick-connect
type charging valve prevents refrigerant from
leaking when the charging hose is connected to
the valve.
Remarks