Mazda 1996 626, Service Manual

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CAUTIONARY POINTS FOR MAINTENANCE
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 R-134a system Remarks
Refrigerant C hlorofluorocarbon-12
(C FC-12)
[CCI
2 F 2 ]
Hydrofluorocarbon-134a
(H FC-134a)
[CH
2 FCF 3 ]
If the refrigerants are mixed or one refrigerant is
used in a system that requires the other, the
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 -1 3 4 a with R -1 2 or using
R -1 3 4 a instead of R -1 2 in an R -1 2 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.
Compressor oil Mineral oil Polyalkylene glycol oil
(PAG oil)
Special compressor oils for R -1 3 4 a 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 -1 2 system can
lower the durability of the NBR and fluorine rub­
ber O-rings.
O-ring Nitrile butadiene rubber
(NBR)
Fluorine rubber High-circulated nitrile
butadiene rubber
(HNBR)
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.
Joint nuts Inch threads Metric threads Thread standards for joint nuts connecting pipes
and hoses have been changed to avoid con­
necting R -1 2 system parts with R -1 3 4 a system
parts.
Joint blocks
— —
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.
Charging valve Screw-on type
Hi: 3 /8 -2 4 UNF
Lo: 7 /16-20 UNF Quick-connect type
Hi: 16mm {0.6 in} dia.
Lo: 13mm {0.5 in} dia.
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.
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