GMC 1989 Light Duty Truck, Repair Manual, Page: 45 / 998

V5 AIR CONDITIONING COMPRESSOR 1B2-1
SECTION 1B2
V5 AIR CONDITIONING COMPRESSOR
CONTENTS
SUBJECT PAGE
D e s c rip tio n .....................................................................................................................................................................................1B2- 1
Theory of O p e ra tio n ................................................................................................................................................................ 1B2- 1
Minor Repair to the C o m p re s s o r..............................................................................................................................................1B2- 2
Clutch Plate and Hub Assem bly Replacem ent.................................................................................................................. 1B2- 2
Pulley and Bearing Assem bly R e p la c e m e n t.....................................................................................................................1B2- 4
Clutch Coil R e p la c e m e n t....................................................................................................................................................... 1B2- 7
Pressure Relief Valve R ep la ce m e n t.....................................................................................................................................1B2- 7
High-Side Pressure and High-Side Low Pressure Cutoff Switches R ep lacem en t.................................................. 1B2- 8
Control Valve R e p la c e m e n t.................................................................................................................................................. 1B2- 9
Major Repair to the C o m p re s s o r..............................................................................................................................................1B2- 9
Shaft Seal R e p la c e m e n t......................................................................................................................................................... 1B2- 9
Front Head Seal, Rear Head Gasket, Rear Valve Plate, Suction Reed Plate and
Cylinder to Rear Head Seal R eplacem ent....................................................................................................................... 1B2-10
Leak T e s tin g ...................................................................................................................................................................................1B2-12
Specifications................................................................................................................................................................................
1 B2-13
Special Tools...................................................................................................................................................................................1B2-14
V5 AIR CONDITIONING COMPRESSOR
DESCRIPTION
THEORY OF OPERATION
The V5 is a variable displacem ent com pressor that can
match all air conditioning dem ands under all conditions
without cycling (figure 1). The basic com pressor m echa­
nism is a variable angle wobble-plate with five axially ori­
ented cylinders. The center of control of the com pressor
displacement is a bellows actuated control valve located in
the rear head of the com pressor that senses com pressor
suction pressure. The wobble-plate angle and com pressor
displacement are controlled by the crankcase-suction pres­
sure 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 com pres­
sor will have m aximum displacem ent. When the A/C capac­
ity 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 con­
trolled by a force balance on the five pistons. A slight eleva­
tion of the crankcase-suction pressure differential creates a
total force on the pistons resulting in a m ovement about the
wobble-plate pivot pin that reduces the plate angle.
The crankcase-suction bleed is routed through the rotat­
ing w obble-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 com pressor m ech­
anism.
Up to 113 g (4 oz.) of oil can collect in the crankcase.
Therefore, it is important when replacing a com pressor that
the oil in the old com pressor crankcase be drained through
the drain plug and m easured (discard after recording
amount).
All replacement com pressors will be shipped with 227 g
(8 oz.) of oil in the crankcase. The oil must be drained and
retained. Then replace the oil in the same am ount as previ­
ously recorded from the old com pressor. Refer to “ Specifi­
cations.”
IDENTIFICATION
An identification label attached to the com pressor pro­
vides the name of the m anufacturer, model num ber and
build code.
When servicing the V5 compressor, keep dirt and foreign
material from getting on or into the com pressor parts and
system. Clean tools and a clean w ork area are important for