C 2500 Truck 2WD V8-5.7L VIN R (1997)
Refrigerant: Vehicle Damage Warnings
General System Repair Precautions
FASTENERS
NOTICE: Always use the correct fastener In the proper location. When you replace a fastener, use ONLY the exact part number for that application.
General Motors will call out those fasteners that require a replacement after removal. General Motors will also call out the fasteners that require thread
lockers or thread sealant. UNLESS OTHERWISE SPECIFIED, do not use supplemental coatings (paints, greases, or other corrosion Inhibitors) on
threaded fasteners or fastener Joint Interfaces. Generally, such coatings adversely affect the fastener torque and Joint clamping force, and may damage
the fastener. When you Install fasteners, use the correct tightening sequence and specifications. Following these Instructions can help you avoid damage
to parts and systems.
PAG OIL
NOTICE: Use only Polyalkylene Glycol Synthetic Refrigerant Oil (PAG) for internal circulation through the R-134a A/C system and only 525 viscosity
mineral oil on fitting threads and O-rings. If lubricants other than those specified are used, compressor failure and/or fitting seizure may result.
REFRIGERANT
NOTICE: R-134a is the only refrigerant approved for use in this vehicle. Use of other refrigerants may result in poor system performance or component
failure.
TOOLS
NOTICE: Tools and equipment used to service R-134a vehicles should be dedicated to R-134a. Since all equipment contains some residual refrigerant
/lubricant, system contamination may occur resulting in poor system performance or component failure.
Replacing O-Ring Seals
Install new GM-approved service replacement air conditioning O-ring seals whenever a joint or fitting is installed, except when the O-ring seals are
provided on new replacement components. Unless service replacement O-ring seals bearing the specified part numbers are used, excessive leakage of
Refrigerant-134a may occur. Refer to the part number for identification.
Coat air conditioning O-ring seals with 525 viscosity refrigerant oil just before installation and slip them onto the flange tube to ensure proper locating
and sealing. To prevent the possibility of swelling and a reduction in sealing effectiveness, do not soak O-ring seals in refrigerant oil. Before installation,
examine O-ring seals and fittings to make sure they have not been nicked or deformed. Replace nicked or deformed pans to prevent refrigerant leakage.
Replacing Dual O-Ring Seals
Install new GM-approved service replacement air conditioning O-ring seals whenever a joint or fitting is disassembled, except when the O-ring seals
are provided on new replacement components. Unless service replacement O-ring seals bearing the specified part numbers are used, excessive leakage
of Refrigerant-134a may occur. Refer to the part number for identification.
This vehicle uses GM's dual O-ring joint design in the system. This design increases the durability of the joint seal by providing a second O-ring seal.
The dual O-ring design consists of:
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An aluminum-alloy, externally threaded fitting which is brazed or welded to an aluminum tube.
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A free-spinning, plated steel internally threaded nut.
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A precision machined, male-piloted aluminum tube end which accommodates two O-rings.
Maintaining Refrigerant Chemical Stability
The life and efficient operation of the air conditioning system depends upon the chemical stability of the refrigerant system. When foreign materials, such
as dirt, air, or moisture, contaminate the refrigeration system, they change the stability of the Refrigerant-134a and polyalkaline glycol (PAG) refrigerant
oil. They will also affect the pressure-temperature relationship, reduce efficiency, and could cause internal corrosion and abnormal wear of moving parts.
The following general practices should be followed to ensure chemical stability in the system:
1. Whenever it becomes necessary to disconnect a hose connection, wipe away any dirt or oil at or near the connection to eliminate the possibility of
dirt entering the system. Both sides of the connection should be capped, plugged or taped as soon as possible to prevent the entrance of dirt and
moisture. (Remember that all air contains moisture. Air that enters any part of the refrigeration system will carry moisture with it, and the exposed
surfaces will collect the moisture quickly.)
2. Keep tools clean and dry. This includes the Manifold Gage Set and all replacement parts
