Table Of Contents - Pontiac Fiero 1988 Service Manual

AIR CONDITIONING 1B-1
SECTION 1B
AIR CONDITIONING
When performing air conditioning diagnosis on vehicles equipped with a catalytic converter, it will be necessary
to WARM the engine to a NORMAL operating temperature BEFORE attempting to idle the engine for periods greater
than five (5) minutes. Once the engine attains normal idle, diagnosis and adjustments can be made.
General Description
1B-1
V-5 A/C System 1B-1
C.C.O.T. A/C System . . . . . . . . . . . . . . . . . . . . 1B-2
A/C System Differences . . . . . . . . . . . . . . . . . . . 1B-2
System Components - Functional . . . . . . . . . . IB-2
System Components - C o n t r o l . . . . . . . . . . . . . 1B-3
Relays and Switches 1B-4
Diagnosis
1B-5
Testing the Refrigerant System . . . . . . . . . . . . . 1B-5
Insufficient Cooling "Quick-Check"
Procedure 1B-5
V-5 A/C System Diagnostic
Procedure 1B-8
C.C.O.T. A/C System Diagnostic
Procedure. 1B-12
Leak Testing . . . . . . . . . . . . . . . . . . . . . . . 1B-16
Service Procedures
. . . . . . . . . . . . . . . . . . . . . 1B-16
O-Ring R e p l a c e m e n t . . . . . . . . . . . . . . . . . . . . . 1B-16
Handling Refrigerant-12 . . . . . . . . . . . . . . . . . . 1B-17
Discharging, Adding Oil, Evacuating
and Charging Procedures-A/C
Systems..... 1B-20
In-Line Air Conditioning
Filter Installation .. 1B-22
Expansion Tube (Orifice) Service . . . . . . . . . . 1B-22
Accumulator Assembly Service . . . . . . . . . . . . 1B-26
On-Vehicle Service
1B-26
Accumulator 1B-26
Blower Motor and Fan Cage . . . . . . . . . . . . . . 1B-26
Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1B-27
High Blower R e s i s t o r . . . . . . . . . . . . . . . . . . . . 1B-27
Pressure Cycling S w i t c h . . . . . . . . . . . . . . . . . . 1B-27
Compressor High Pressure Switches . . . . . . . . 1B-27
Expansion Tube ( O r i f i c e ) . . . . . . . . . . . . . . . . . 1B-28
A/C Module Wiring Harness . . . . . . . . . . 1B-28
A/C Controller & Fan Switch 1B-28
Temperature Control Cable . . . . . . . . . . . . . . . 1B-30
Clutch Relay 1B-31
Recirculating Actuator 1B-31
A/C Mode Actuator . . . . . . . . . . . . . . . . . . . . . 1B-32
Heater C o r e . . . . . . . . . . . . . . . . . . . . . . . . 1B-32
Coupled Hose A s s e m b l y . . . . . . . . . . . . . . . . . . 1B-32
Inlet Tube and Hose Assembly . . . . . . . . . . . . 1B-32
A/C Outlet Tube Assembly . . . . . . . . . . . . . . . 1B-33
Evaporator Core 1B-34
Condenser 1B-35
A/C Compressor 1B-35
Special A / C Tools
1B-37
Specifications
1B-37
GENERAL DESCRIPTION
Currently there are two different air condition-
ing systems are available:
1. 4-Cylinder (2.5 Liter, LR8, V.LN. Code
R) V-5
2. 6-Cylinder (2.8 Liter, L44, V.LN. Code
9) HR-6
All air conditioning systems that use the fixed
displacement R-4 or HR-6 compressor are referred to
as C.C.O.T. (Cycling Clutch, Orifice Tube) type sys-
tems. This is the same system that has been used on
all General Motors vehicles in the past several years.
Air conditioning systems that use the variable dis-
placement compressor are referenced to as V-5 type
systems. The two systems are described below.
T h e V - S A / C S y s t e m
The V5 is a variable displacement compressor
that can match the automotive air conditioning
J - u n d e r
all conditions without cycling. The
basic compressor mechanism is a variable angle wob-
ble-plate with five axially oriented cylinders. The cen-
ter 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 dis-
placement 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 displace-
ment. 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 eleva-
tion of the crankcase-suction pressure differential cre-
ates a total force on the pistons resulting in a
movement about the wobble-plate pivot pin that
reduces the plate angle.