PONTIAC FIERO 1988 Service Repair Manual

AIR CONDITIONING: COMPRESSOR CONTROLS
667, ELECTRONIC:
(Continued from previous page)
SYSTEM CHECK TABLE SYSTEM DIAGNOSIS
times
ACTION
1. Turn the Ignition Switch to RUN and start the
engine
Set the
A/C Mode to OFF then to MAX
2. Alternately select OFF and MAX several
Clutch plate movement can be seen on the front
1 ISOLATION TEST (TABLE I) of the compressor pulley
1 I If the clutch does not engage, proceed to step 4 (
EXPECTED RESULT
A click can be heard when the clutch engages
Verify that the clutch engages in MAX
If the clutch operates as expected, continue to
1 St€??J 3 I
V6 VIN S
r Use the isolation Test below to choose the
proper diagnostic tests.
Tests follow the isolation Test.
3. Select MAX mode to engage clutch Check
that air from the coolant fan can move
freely through condensor
Feel the input (cool) and output (warm) pipes to
the compressor
If there is not a wide temperature difference after
the compressor has run for several seconds, see
Section
1B for refrigerant and Compressor
diagnostics
4. Turn off the ignition
Check the refrigerant charge, according to the
procedures in Section
1B
If the refrigeramt charge is low, follow the
procedures in Section
1B for refrigerant diagnosis
If the refrigerant charge is normal, isolate the
conditions using the procedures which follow in
the System Diagnosis
(ISOLATION TEST (TABLE 1) continued on
facing page)
Measure: VOLTAGE
At: AIC COMPRESSOR CONTROL RELAY
CONNECTOR (Disconnected)
Conditions:
ignition Switch: RUN (Engine need
not
be running)
c A/@ Mode: NORM
* Temperature Outside Car: Above 60°F
(16°C)
Refer to System Diagnosis when a result is not normal. Measure
Between
C (PNKIBLK)
& Ground
Correct
Voltage
Battery
For
Diagnosis
Check GAGES
Fuse and PNKi
BLK (39) wire
for an open

(Continued on next page)
AIR CONDITIONING: COMPRESSOR CONTROLS
C67, ELECTRONlG
(ISOLATION TEST (TABLE 1) continued A: ECM COMPRESSOR CONTROL TEST A:
ECM COMPRESSOR CONTROL TEST
If action is correct, do Test A.
from
facing page)
(TABLE 2)
Measure: RESISTANCE
At: ECM CONNECTOR (Disconnected)
Conditions:
r Ignition Switch: OFF
.a Negative Banery Terminal
Disconnected
E (DK GRNI
WHT) &
Ground
(TABLE 1)
Measure: VOLTAGE
At: ECM CONNECTOR (Disconnected)
Conditions:
r Ignition Switch: RUN (Engine not
running)
AIC Mode: NORM
AIC Compressor Control Relay
Connected
Temperature Outside Car: Above 60°F
(I 6°C)
For
Diagnosis
See 1
Measure
Between
B9 on Conn 61
(GRY) &
Ground
Battery
.a If
resistance is correct proceed to Table 3.
1. Check that Power Steering Switch is closed.
If switch is open, replace it. Check for an
open in the GRY (901) wire and
BLKIWHT
(450) wire.
Correct
Resistance
0 ohms For
Diagnosis
See 1
See 2
Measure
Behnreen
B8 on Conn Cl
(DK GRNi
WHT) &
Ground
A2 on Conn
61
(LT BLU) &
Ground
Check
DK
GRNNHT
(59) wire for
an open.
If wire is good,
do Test C
If voltages are correct proceed to Table 2.
1. Check for open in DK
GRNNHT (59) wire.
2. Check for open in LT BLU (905) wire. If wire
is good, replace
AIC Compressor Control
- Relay.
Correct
Voltage
Battery
Battery
If
voltages are correct leave
AlC Com-
pressor Control Relay Connector
disconnected and go to Table
2.
lSOLATlON TEST (TABLE 2)
Connect: FUSED JUMPER
At:
AIC COMPRESSOR CONTROL RELAY
CONNECTOR (Disconnected)
Conditions:
Ignition Switch: RUN (Engine need
not be running)
r A/C Mode: NORM
.a Temperature Outside Car: Above 60°F
(1 6°C)
Jumper
Between
E (DK GRNI
WHT) & A
(DK GRN)
Correct
Action
Clutch
Engages
For
Diagnosis
Do Test B

AIR CONDITIONING: COMPRESSOR CONTROLS
(Continued from previous page) B: AIC COMPRESSOR CLUTCH TEST
A: ECM COMPRESSOR CONTROL TEST
(TABLE
3)
Connect: FUSED JUMPER
At: ECM CONNECTOR (Disconnected)
Conditions: lgnition Switch: RUN (Engine not
running)
@ AIC Mode: NORM
Temperature Outside Car: Above
60 OF
(16°C)
Jumper Correct
Between Action Diagnosis
engages
A2
on Conn
61
(LT BLU)
& Ground
If action is correct but A/C system does not
operate under normal conditions, condition
is due to ECM. Refer to Section 6E for ECM
diagnostics. Compressor
Control Relay
operates and
AfC Clutch
Between 1 Voltage I Diagnosis
Measure:
VOLTAGE
At: COMPRESSOR CLUTCH CONNECTOR
(Disconnected) Ignition Switch: RUN (Engine
not
running)
r AIC Mode: NORM
@ AIC Compressor Control Relay
disconnected
AIC Compressor Control Relay
terminals A and E jumpered
r Temperature Outside Car: Above 60°F
(1 6°C)
See 1
B (DK GRN) & /
Ground I See 1
Measure I Correct
(DK GRN) '1 Battery I See 2 A (BLK)
For
- -
e If voltages are correct but clutch does not
engage, replace the Compressor Clutch.
1. Check for open in DK GRN (959) wire.
2. Check for open in BLK (150) wire.
6: AIC COMPRESSOR FUNCTlON
CONTROL TEST
Measure: VOLTAGE
At: AIC CONTROL HEAD
Conditions: Ignition Switch: RUN (Engine need
not be running)
@ AIC Mode: NORM
Temperature Outside Car: Above
60°F
(16°C)
Measure I Correct
Between Voltage
& Ground
If voltages are correct, go to
61.
1. Check for open CLSTR Fuse or open
For
Diagnosis
See 1
B (LT GRN) &.
Ground -
C1. Remove the connectors from the A/C Pressure
Cycling Switch and the
A/C High Pressure Cut-
Out Switch and connect a fused jumper between
the terminals of the connectors.
If either switch is open, battery voltage will
be present at al E of the AIC Corn-
pressor Control Relay when the jumper is
connected.
Battery
If the Ale Pressure Cycling Switch is open,
refer to Section
1B to check for normal
refrigerant charge. If refrigerant charge is
normal replace the switch. If refrigerant
charge is low, follow procedures in Section
1B for refrigerant diagnostics. Replace
AfC
Control Head
0 If
the NC Nigh Pressure Cut-Out Switch is
open replace
it.

AIR CONDITIONING: COMPRESSOR CONTROLS
667, ELECTRONIC
r If both switches are good but battery volt-
age is not present at the
A/C Compressor
Control Relay, check the wiring between
switches for an open (see schematic).
SYSTEM DlPaGNOSlS
V8 VINF, V8 VIN 8
s Use the Isolation Test below to choose the
proper diagnostic tests.
r Tests follow the Isolation Test.
lSOLATlON TEST (TABLE 2)
Connect: FUSED JUMPER
At:
A/C PRESSURE CYCLING SWITCH
CONNECTOR (Disconnected)
Conditions: Ignition Switch: RUN (Engine need
not be running)
Q NC Mode: NORM
Q Temperature Outside Car: Above 60°F
(1 6°C)
I Jumper I Correct I For
lSOLATlOlU TEST (TABLE 1)
I Measure: VOLTAGE
AIC Mode:
NORM
@ Temperature Outside Car: Above 60°F
(1 6°C)
At:
AIC PRESSURE
CYCLING SWITCH
CONNECTOR (Disconnected)
Conditions:
lgnition Switch: RUN (Engine need
not be running) Between
B (LT GRN) &
A (LT
BLU)
If action is correct, refer to Section 1B for
procedure to check refrigerant pressure. If
refrigerant pressure is
normal, replace the
I (zz) & I Battery I Do Test B I
Measure
Between
A: AIC COMPRESSOR CLUTCH TEST
Action
Clutch
Engages
Diagnosis
Do Test A
Correct
Voltage
.
If voltage is correct, leave Pressure Cycling
Switch disconnected and go to Table
2.
Measure: VOLTAGE
At:
A/C COMPRESSOR CLUTCH
CONNECTOR (Disconnected)
Conditions:
lgnition Switch: RUN (Engine not
running)
0 A/C Mode: NORM
Temperature Outside Car: Above
60°F
(16°C)
For
Diagnosis
(Continued on next page)
Measure
Betvveen
B (DK GRN) &
Ground
B (DK GRN) &
A (BLK)
Q If voltages are correct but clutch does not
engage, replace the Compressor Clutch.
1. Check that A/C Nigh Pressure Cut-Out
Switch is closed (see schematic).
If it is
open, replace it. Check for
an open in the
LT BLU (67) and DK GRN (59) wires.
2. Check for an open in the BLK (150) wire.
Check that ground 6112 is clean and tight.
Correct
\joltage
Battery
Battelr
For
Diagnosis
See 1
See 2

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
R
E B
I I I I I
I
I
I
I
I I I
8Y DESIGN 7% OUTSIDE AIR I
:
I
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.