1988 PONTIAC FIERO Service Repair Manual

AIR CONDITIONING: COMPRESSOR CONTROLS
C67, ELECTRONIC
(Continued from previous page) ISOLATION TEST (TABLE 1) A: AIC COMPRESSOR CLUTCH TEST 1
B: A/C COMPRESSOR FUNCTION
CONTROL TEST
At: AIC CONTROL HEAD
Conditions:
@ lgnition Switch: RUN
AIC Mode: NORM
Temperature outside car: above 60°F
I (16°C)
Measure
Between
-
Replace AJC
M (BRNIWHT)
& Ground
If voltages are correct, check for an open
in
the LT GRN (66) wire.
1. Check for an open CLSTR Fuse or open
BRNIWRT (950) wire.
Correct
Voltage
SYSTEM DIAGNOSIS
For
Diagnosis
Battery
Do the tests listed for your symptom in the
Symptom Table below.
Tests follow the Symptom Table.
See 1
Measure: VOLTAGE
At: PRESSURE CYCLING SWITCH
CONNECTOR (Disconnected)
Conditions: lgnition Switch: RUN (Engine need
not be running)
AIC Mode: NORM
a Temperature Outside Car: Above 60°F
(16°C)
I Measure ( Correct ( For (
Between I Voltage 1 Diagnosis I
1 If voltage is correct, leave Pressure Cycling 1
B (LT GRN) &
Ground
Switch disconnected and go to Table 2.
lSOLATlON TEST (TABLE 2)
Battery
Connect: JUMPER
At: PRESSURE CYCLING
SWITCH
CONNECTOR (Disconnected)
Conditions: lgnition Switch: RUN (Engine need
not be running)
@ AIC Mode: NORM
a Temperature Outside Gar: Above 60°F
Do Test B
I Between I Action I Diagnosis I
(16°C)
a If action is correct but A/C Compressor
Clutch does not engage under normal oper-
ating conditions, refer to Section
1B for pro-
cedure to check refrigerant pressure. If
refrigerant pressure is normal, replace the
Pressure
Cycling Switch.
For Jum~er
B (LT GRN) &
A (LT BLU)
At: Ale COMPRESSOR CLUTCH
CONNECTOR (Disconnected)
@ lgnition Switch: RUN (Engine not
@ AIC Mode: NORM
Pressure Cycling Switch Connected
Temperature Outside Car: Above
60°F
1. Check that AIC High Pressure Cut-Out
Switch
is closed (see schematic). If it is
open, replace it. Check for
an open in the
LT BLU (67) wire, the DK BLU (67) wire
and the
DK GRN (59) wire.
2. Check for
an open in the BLK (150) wire.
Check that ground 6112 is clean and
Correct
.
Clutch
Engages Do
Test A

AIR CONDITIONING: COMPRESSOR CONTROLS
B: AIG COMPRESSOR FUNGTlON
CONTROL TEST
Measure: VOLTAGE
At: AIG CONTROL HEAD
Conditions:
e Ignition Switch: RUN
@ A/C Mode: NORM
@ Temperature outside car: above 60°F
(16°C)
1 Measure I Correct 1 For 1
Between I Voltage I Diagnosis I
1 ) 1 Battery 1 See 1 I
r If voltages are correct, check for an open in
the LT
GRN (66) wire.
B (LT GRN) &.
Ground
1. Check for an open CLSTR Fuse or open
BRN
(950) wire.
The compressor for the air conditioning system
is belt driven by the engine through the Com-
pressor Clutch. The clutch allows the compressor
to be disengaged when air conditioning is not re-
Battery
quired or to remove the air conditioning load from
the engine when necessary. Replace
A/C
Control Head
Operation of the compressor depends on the
particular A/C mode selected by the driver. When
the
A/C Mode is in MAX, NORM, BI-LEVEL or
DEF battery voltage is applied through the
CLSTR Fuse and
A/C Control Head Mode Selec-
tor Switch to the remaining circuits.
V6 VIN S
For vehicles equipped with the V6 VIN S
engine the path to the
A/C Compressor Control
Relay is through the
AlC Pressure Cycling
Switch and the
A16 Nigh Pressure Cut-Out
Switch which are both normally closed. The
Ale Pressure Cycling Switch opens when
refrigerant pressure drops to a point where the
evaporator may begin to ice.
It closes again
when the pressure rises to the point where
addi-
tional cooling is required. This action causes the
compressor to cycle on and off. The
Ale High
Pressure Cut-Out Switch opens when
refrigerant pressure is too high for
nomd oopr-
ation.
The AIC Compressor Control Relay is operated
by the EGM. When the ECM receives the
A/C ON
signal at Terminal
B8, it grounds Terminal A2,
energizing the relay. When the relay is energized,
voltage is applied to the
A/C Compressor Clutch
through the contacts of the relay. If the ECM de-
termines that engine load should be reduced,
such as during full throttle, the
A/C Compressor
Control Relay is de-energized which removes volt-
age from the
A/C Compressor Clutch thus remov-
ing the
A/C load from the engine.
V8 VlN F, V8 VllU 8
From the AlC Control Head voltage is
applied to the
A/@ Cornpressor Clutch through
the Pressure Cycling Switch and the
A/@ High
Pressire Cut-Out Switch. The Pressure Cycling
Switch is normally closed but opens when
refrigerant pressure drops below
172 kPa (25
psi). It closes again when refrigerant pressure
rises enough that additional cooling is required.
This action causes the
A/C Compressor to cycle
on and off so that the evaporator temperature does
not drop low enough to cause icing. The
A/
C High Pressure Cut-Out Switch opens if
refrigerant pressure rises to a point which is too
high for normal operation.
When voltage is applied to the compressor
clutch it is also applied to the ECM at
Terminal
B8 on Connector 61. The ECM will then increase
the engine idle speed while the
A/G Compressor
Clutch is engaged.
From the
AlC Control Head voltage is
applied to the
A/C Compressor Clutch though
the Pressure Cycling Switch and the AIC High
Pressure Cut-Out Switch. The Pressure
Cychg
Switch is normally closed but opens when
refrigerant pressure
drops below 172 kPa (25
psi). It closes again when refrigerant pressure
rises enough that
additional cooling is required.
This action causes the
A/C Compressor to cyde
on and off so that the evaporator teqerature
does not drop low enough to cause icing. The
A/C High Pressure Cut-Out Switch opens if
refrigerant pressure becomes too high for nor-
mal operation.

AIR CONDITIONING: AIR DELIVERY
!E 667, ELECTRONIC I
FUSE - BLOCK - TEMPERATURE YELLOW
SELECTOR WIRE (996)
FULLY COLD GREATER THAN
BATTERY VOLTAGE
MINUS
0.3 VOLTS
FULLY HOT LESS THAN
0.3 VOLTS

41
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E B
I I I I I
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8Y DESIGN 7% OUTSIDE AIR I
:
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a 06
A

AIR CONDITIONING: AIR DELIVERY I g
667, ELECTRONIC
TROUBLESHOOTING
HINTS
Try the following checks before doing System
Diagnosis.
1. Check for vacuum to the vacuum tank at the
BLACK Hose from the engine vacuum
source and at the VIOLET Rose to the
AIC
Vacuum Solenoid Module.
Check the operation of the Temperature
Valve by setting the Temperature Selector
to COLD and then moving it to ROT.
Observe that the valve moves through its
full range each time the Temperature Selec-
tor is changed from one end of the range to
the other. If the valve is not fully closing or
opening, check that the valve is free to move
and that none of the linkage is binding.
3. Check that Heater Water Bypass Valve
operates in MAX
AIC Mode.
Go to the AIC System Check in 8A-62 for a
guide to normal operation of the Air
Delvery
System.
Go to System Diagnosis
in this section for
diagnostic tests.
SYSTEM DIAGNOSIS
Engine warm and running at idle.
If air flow does not come from the proper
outlets under one or more operating modes,
at least one of the air valves is not moving to
the proper position.
@ Check the operation of the air valves using
the following chart. Put Blower switch in
HI
to give a strong flow of air.
COMPONENT LOCATION Page-Figure
AIC Defrost Vacuum Actuator ..... Behind IIP, on LH side of plenum .............
AIC Temperature Door Motor ...... Behind IIP, on RH side of plenum. ............
AIC Vacuum Solenoid Module ...... Behind IIP, on RH side of plenum. ............
Check Valve. .................... Behind engine, to right of master brake cylinder.
Fuse Block.
..................... Behind LH side of IIP, below light switch. ......
Neater Water Bypass Valve. ....... RH front of engine
Lower Mode Vacuum Actuator
..... Behind IIP, on LH side of plenum .............
Outside Air Vacuum Actuator. ..... Behind IIP, on RH side of plenum. ............
Upper Mode Vacuum Actuator ..... Behind IIP, on LH side of plenum .............
.. Vacuum Tank ................... Lower LH front corner of engine compartment
6200
.......................... Behind IIP, left of steering column ............
S125. .......................... Engine harness, top LH rear of engine .........
........ S201. .......................... IIP harness, behind instrument cluster.
........ S205. .......................... IIP harness, behind instrument cluster.
(Disconnected)
Condition:
IgnEon Swgch: ON
AIR DOOR POSITION TABLE A: AIC CONTROL HEAD VOLTAGE TEST
Measure
Between I Correct Vdtage / For Diagmsk I
Conditions: ignition Switch: RUN (Engine Running)
Blower Switch: HI
I"(BRNIWIFDI & Ground Battery ( See1 I
Measure: VOLTAGE
At:
A/C CONTROL HEAD CONNECTOR 61
I I
@ If voltages are correct, go to tests B and C.
(Continued on facing page)
Mdifional tests of the AIC Vacum System are
(950) wire.
2- ~hd for op in BLK (150) rrire to given in Seclion 1B.

AIR CONDITIONING: AIR DELIVERY
(Continued from previous page)
Temperature Valve
The Temperature Valve is positioned by the
A/C Temperature Valve Motor which is con-
trolled by the Temperature Selector. When the
Temperature Selector is moved to the COLD
position, battery voltage is applied to the Con-
trol Input of the
AIC Temperature Valve Motor
on the YEL
(996) wire. The circuits in the Ale
Temperature Valve Motor cause the motor to
move the Temperature Valve to the COLD posi-
tion which blocks all air from passing through
the Heater Core.
As the Temperature Selector is moved from
the COLD to ROT position, the voltage at the
control input of the
AIC Temperature Valve
Motor drops to about
0.3 volts at the HOT
position. The changing voltage level causes the
motor to move the valve to the position corre-
sponding to the setting of the Temperature
Selector.
Outside Air Valve
The Outside Air Valve determines whether
air will be drawn from the outside air inlet or
from inside the car. The valve is in position
B
(see schematic) in all modes except MAX, per-
mitting outside air to enter. In the MAX Mode,
the Outside Air Solenoid is energized applying
vacuum to the Outside Air Vacuum Actuator
which moves the valve to position A. Air from
inside the car is then recirculated to get max-
imum cooling from the
air conditioning system.
Heater Water Bypass Valve
In all operating modes except MAX, engine
coolant circulates through the heater core to
heat the
air from the Blower. When the MAX
Mode is selected, the
Neater Water Bypass
valve is operated by the Outside Air Vacuum
Actuator.
HeatIDefrost Valve
With the system OFF, or with the BI-LEVEL
or HEATER Modes selected, vacuum is
applied to the
AIC Defrost Vacuum Actuator.
The bellows contract and the
HeatIDefrost
Valve moves to B position. Most of the air flows
out of the
Footwell Air Outlets. In all other
Modes no vacuum is applied to the Vacuum
Actuator and the
HeatIDefrost Valve remains
in position A forcing most of the air out of the
Windshield Air Outlets.
Upper and Lower Mode Valves
The two Mode Valves determine the amount
of
air flow to the Instrument Panel Air Outlets.
When the Mode selected is MAX, NORMAL or
VENT, vacuum is applied to both the Upper
and Lower Mode Vacuum Actuators. Both
valves then move to position
B and all air flows
out the Instrument Panel Air Outlets. In the
BI-LEVEL mode,
vacuumis applied only to the
Lower Mode Vacuum Actuator which moves the
Lower Mode Valve to position
B. The Upper
Mode Valve moves to position
A. In these posi-
tions some air flows out of the Instrument
Panel Air Outlets and the rest flows out the
Footwell Air Outlet. In HEATER, DEF and
OFF no vacuum is applied to either Vacuum
Actuator and both valves move to position A.
AU. air then flows to either the Footwell Air
Outlets or the Windshield Air Outlets depend-
ing on the position of the
NeatIDefrost Valve.