PRECAUTIONS
HA-11
< PRECAUTION >
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The oil contained inside the vacuum pump is not compatible with the
specified oil for HFC-134a (R-134a) A/C systems. The vent side of
the vacuum pump is exposed to atmospheric pressure so the vac-
uum pump oil may migrate out of the pump into the service hose.
This is possible when the pump is switched off after evacuation (vac-
uuming) and hose is connected to it.
To prevent this migration, use a instruction valve situated near the
hose-to-pump connection, as follows.
• Usually vacuum pumps have a instruction isolator valve as part of the
pump. Close this valve to isolate the service hose from the pump.
• For pumps without an isolator, use a hose equipped with a instruction
shut-off valve near the pump end. Close the valve to isolate the
hose from the pump.
• If the hose has an automatic shut off valve, disconnect the hose
from the pump: as long as the hose is connected, the valve is open
and lubricating oil may migrate.
Some one-way valves open when vacuum is applied and close
under a no vacuum condition. Such valves may restrict the pump's
ability to pull a deep vacuum and are not recommended.
MANIFOLD GAUGE SET
Be certain that the gauge face indicates HFC-134a (R-134a). Make
sure the gauge set has 1/2
″
-16 ACME threaded connections for ser-
vice hoses. Confirm the set has been used only with refrigerant
HFC-134a (R-134a) along with specified oil.
SERVICE HOSES
Be certain that the service hoses display the markings described
(colored hose with black stripe). All hoses must include positive shut-
off devices (either instruction or automatic) near the end of the hoses
opposite the manifold gauge.
SERVICE COUPLERS
RHA270D
SHA533D
RHA272D