Basic Compressor Mechanism Is A Variable Angle Wob - Pontiac Fiero 1988 Service Manual

1D3-2 V-5 AIR CONDITIONING COMPRESSOR OVERHAUL
lines. The other rear head is the same as past models,
except that some models have replaced the low
pressure cut-out switch with a coolant fan switch. The
low pressure cut-out switch on these models will also
be located in a refrigerant line. See Section IB for
specific locations.
V 5 COMPRESSOR -THEORY OF OPERATION
The V5 is a variable displacement compressor
that can match the automotive air conditioning
demand under all conditions without cycling. The
basic compressor mechanism is a variable angle
wobble-plate with five axially oriented cylinders. The
center of control of the compressor displacement is a
bellows actuated control valve located in the rear head
of the compressor that senses compressor suction
pressure. The wobble-plate angle and compressor
displacement are controlled by the crankcase-suction
pressure differential. When the A/C capacity demand
is high, the suction pressure will be above the control
point; the valve will maintain a bleed from crankcase
to suction; no crankcase-suction pressure differential;
and the compressor will have maximum displacement.
When the A/C capacity demand is lower and the
suction pressure reaches the control point, the valve
will bleed discharge gas into the crankcase and close 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 total
force on the pistons resulting in a movement about the
wobble-plate pivot pin that reduces the plate angle.
The compressor has a unique lubrication system.
The crankcase-suction bleed is routed through the
rotating wobble-plate for lubrication of the
wobble-plate bearing. The rotation acts as an oil
separator, which removes some of the oil from the
crankcase-suction bleed, rerouting it to the crankcase
where it can lubricate the compressor mechanism.
Up to 4 oz. of oil can collect in the crankcase.
Therefore, it is important when replacing a compressor
that the oil in the old compressor crankcase be drained
thru the drain plug and measured (discard after
recording amount).
All replacement compressors will be shipped with
8 oz. of oil in the crankcase, the oil must be drained and
retained. Then replace the oil in the same amount as
previously recorded from the old compressor.
1 - REAR H E A D
2 - SUCTION PORT
3 - REAR HEAD GASKET
4 - VALVEPLATE
5 - SUCTION REED PLATE
6 - CLUTCH COIL
7 - PULLEY
8 - DRIVE PLATE
9 - PULLEY BEARING
1 0 - SHAFT KEY
1 1 - SHAFT NUT
1 2 - FRONT SEAL RETAINER
1 3 - FRONTSEAL
1 4 - F R O N T S E A L " 0 " R I N G
1 5 - FRONT HEAD
1 6 - COMPRESSOR CONTROL
VALVE
1 7 - HIGH PRESSURE RELIEF
VALVE
Fig. 3 V 5 Compressor - Cross Section