Dodge R1500 1999 Service Manual page 131

Refrigerant R-12 based systems use mineral oil, while R-134a
systems use synthetic Polyalkylene Glycol (PAG) oils. Using a mineral
oil based lubricant with R-134a will result in A/C compressor failure
due to lack of proper lubrication.
Following are the most common R-134a refrigerant oils used by
most domestic vehicles:
Chrysler Corp., Eagle & Jeep
Use ND-8 PAG oil, SUN PAG 56 oil, SP-10 PAG Oil, or SP-20 PAG
oil.
Ford Motor Co.
Use YN-12B or YN-12C PAG Refrigerant Oil (specification WSH-
M1C231-B) or SP-20 PAG Oil (specification WST-M1C231-B2).
General Motors
On all models except Saturn, use PAG Refrigerant Oil (Part
No. 12345923). On Saturn, use Saturn PAG refrigerant oil.
NOTE: PAG oil absorbs moisture very rapidly, 2.3-5.6 percent by
weight as compared to a mineral oil absorption rate of .005
percent by weight.
NOTE: Use ONLY the specified oil for the appropriate system or A/C
compressor. Always check the underhood A/C specification
label or A/C compressor label before adding refrigerant oil
to A/C system.
SYSTEM SERVICE VALVES
SCHRADER-TYPE VALVES
NOTE: Although similar in construction and operation to a tire
valve, NEVER replace a Schrader-type valve with a tire
valve.
Schrader valve is similar in construction and operation to a
tire valve. See Fig. 4. When a test gauge hose is attached (hose has
built-in valve core depressor), Schrader stem is pushed inward to the
open position and allows system pressure to reach the gauge.
If test hose being used does not have a built-in core
depressor, an adapter must be used. Never attach hoses or adapters to
a Schrader valve unless it is first connected to manifold gauge set.
Fig. 4: Schrader Service Valve (Compressor Location Shown)
SPECIAL VALVE CONNECTORS
On some General Motors models, thread size on high-side