GMC chervolet camaro 1999 Service Manual page 214

HVAC
The variable displacement orifice tube (VDOT) system
is comprised of the following components:
• A variable displacement compressor (1)
• A fixed expansion tube (5)
This system matches the air conditioning demands
under
all
modes without cycling. The basic compressor
mechanism is a variable angle wobble-plate with
five cylinders. The five cylinders are oriented around a
common axis. The center of controLof the compressor
displacement is the control valve. The control valve
is actuated by a .bellows. The control valve is located in
the rear head of the compressor (1) that senses
compressor suction pressure. the crankcase-suction
pressure differential controls the following-conditions:
• The wobble-plate angle
• The compressor displacement
When the A/C capacity demand is high, the suction
pressure will be above the control point. The valve
performs the following functions:
• Maintains a bleed discharge gas into the
crankcase
• Closes off a passage from the crankcase to the
suction plenum
The angle of the wobble-plate is controlled by a force
balance on the five pistons. A slight elevation of
the crankcase suction pressure differential creates a
total force on the pistons. The force on the pistons
produces a movement about the wobble-plate pivot pin
that reduces the plate angle.
Refrigerant R-134a
Caution: Avoid breathing the A/C Refrigerant 134a
(R-134a) and the lubricant vapor or the mist.
Exposure may irritate the eyes, nose, and throat.
Work In
a
well ventilated area. In order to remove
R-134a from the A/C system, use service
equipment that is certified to meet the
requirements of SAE J 2210 (R-134a recycling
equipment). If an accidental system discharge
occurs, ventilate the work area before continuing
service. Additional health and safety information
may be obtained from the refrigerant and lubricant
manufacturers. ·
Refrigerant performs the following functions in the air
conditioning system:
• Absorbs heat
• Carries heat
• Releases heat
These vehicles use Refrigerant-134a (R-134a).
Refrigerant-134a is a nontoxic, nonflammable, clear,
colorless liquified gas.
HVAC System - Manual 1-123
Handling Refrigerant R-134a
Caution: Avoid breathing the A/C Refrigerant 134a
(R-134a) and the lubricant vapor or the mist.
Exposure may irritate the eyes, nose, and throat
Work in
a
well ventilated area. In order to remove
R-134a from the AIC system, use service
equipment that is certified to meet the
requirements of SAE J 2210 (R-134a recycling
equipment). If an accidental system discharge
occurs, ventilate the work area before continuing
service. Additional health and safety information
may be obtained from the refrigerant and lubricant
manufacturers.
Important:
• Use only the approved lubricant for the R-134a
system and the R-134a components. If lubricants
other than those specified are used, compressor
failure may occur. Coat all of the fittings and
the 0-ring seals with a clean approved refrigerant
oil. This action will provide a leak-proof seal
and to aid in assembly and disassembly.
• Do not store or .heat the refrigerant containers
above 125°F (52°C).
• Do not heat a refrigerant container with an open
flame. If the container must be warmed, place
the bottom of the container in a pail of warm water.
• Do not drop, puncture, or incinerate the
refrigerant containers.
• Refrigerant will displace oxygen. Work in
well-ventilated areas in order to prevent
suffocation.
• Do not introduce compressed air to any refrigerant
container or refrigerant component. The action
may cause the contamination of the refrigerant.
• If it is necessary to carry a container of Dot CFR
Refrigerant-134a in a vehicle, do not carry it in
the passenger compartment.
Handling Compressor Oil
Use approved compressor oil from a closed, sealed
container. When adding refrigerant oil, the transfer
device and container should be clean and dry to
minimize the possibility of contamination. Refrigerant
oil is moisture-free and will readily absorb moisture
from the air. Do not open the oil container until
the service procedure requires oil. Cap the oil
immediately after use. Always store compressor oil in
a closed sealed container. Compressor oil left in
open or improperly sealed containers will absorb
moisture. Do not reuse oil that has been removed from
the refrigeration system. Dispose of used oil properly,
according to local regulations.