1988 PONTIAC FIERO check engine

AIR CONDITIONING 1B-1
SECTION 1B
R COND
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.
CONTENTS
.................. General Description .................................. 1B-1 Accumulator Assembly Service .1B-19
.......................... C.C.O.T. A!C System ................................ 1B-1 On-Vehicle Sewice ..... 1B-20
....................................... System Components - Functional ................. 1B-2 Blower Motor .1B-20
..................................... System Components - Control ..................... 1B-3 Hi-Blower Relay 1B-20
...................................... Relays and Switches ................................... 1B-3 Blower Resistor 1B-20
Diagnosis ................................................. 1B-5 Controller, Blower Switch or Vacuum
................................................ Testing the Refrigerant System ...................... 1B-5 Valve .lB-20
Insufficient Cooling "Quick-Check Temperature Control Cable ....................... .1B-20
.................................... Procedure.. ............................................. 1B-5 Vacuum
Harness .lB-20
C.C.O.T. A/C System Diagnostic Control Wiring Harness ........................... .1B-20
..... ................................. Procedure.. ............................................. 1B-8 Heater
Core .. .lB-21
................................ Leak Testing ........................................... 1B-12 Lower Heater Outlet 1B-21
............................... Service Procedures ................................. .1B-12 Heater Module Case .lB-21
.......................... O-Ring Replacement ................................ .1B- 12 Pressure Cycling Switch .1B-21
....................................... Handling Refrigerant- 12 ............................ .1B- 13 Vacuum Tank .lB-21
Discharging, Adding Oil, Evacuating Liquid Line .......................................... .1B-23
and
Charging Procedures - AIC Accumulator ......................................... .1B-23
.................................... Systems .............................................. .1B-14 Evaporator Core .1B-24
In-Line Air Conditioning Evaporator Case .................................... .1B-24
.......................................... Filter
Installation.. .................................. .1B- 18 Compressor .lB-24
.............................................
................ Expansion Tube (Orifice) Service .1 B- 19 Condenser IB-24
GENERAL DESCRIPTION
All engines are equipped with a fixed displace- evaporator temperature. The pressure cycling switch
ment (R-4) air conditioning compressor. This
com- is the freeze protection device in the system and
pressor may cycle on and off under normal air
senses refrigerant pressure on the suction side of the
conditioning demand. system. This switch is located on a standard
Schrader- -
All air conditioning systems that use the fixed
displacement R-4 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.
The C.C.O.T. NG System
The Cycling Clutch Orifice Tube (C.C.O.T.)
refrigeration system is designed to cycle a compressor
on and off to maintain desired cooling and to prevent
evaporator freeze. Passenger compartment comfort is
maintained by the temperature lever on the controller.
Control of the refrigeration cycle (on and off
operation of the compressor) is done with a switch
which senses low-side pressure as an indicator of type
valve low-side fitting. During air temperatures
over 10°C
(50°F), the equalized pressures within the
charged
A/C system will close the contacts of the
pressure switch. When an air conditioning mode
(max, norm, bi-level, defrost) is selected, electrical
energy is supplied to the compressor clutch coil. AS
the compressor reduces the evaporator pressure
to
approximately 175 kPa (25 psi), the pressure switch
will open, de-energizing the compressor clutch.
As
the system equalizes and the pressure reaches approxl-
mately 315 kPa (46 psi), the pressure switch contacts
close, re-energizing the clutch coil. This cycling
coy
tinues and maintains average evaporator discharge air
temperature at approximately 1°C (33°F). Because of
this cycling, some slight increases and decreases of
engine speedlpower may be noticed under certain con-
ditions. This is normal as the system is designed
to
cycle to maintain desired cooling, thus preventing
evaporator freeze-up.

AIR CONDITIONING 1 B-3
A low-side pressure Schrader valve service fit-
ting is located near the top of the accumulator. A
similar Schrader fitting may be provided for mounting
the pressure cycling switch. It is not necessary to dis-
charge the system to replace the switch. The accumu-
lator is serviced only as a replacement assembly.
Heater Core
The heater core heats the air before it enters the
car. Engine coolant is circulated through the core to
heat the outside air passing over the fins of the core.
The core is functional at all times (no water valve) and
may be used to temper conditioned air in
A/C mode,
as well as heat or vent mode.
SYSTEM COMPONENTS --- CON"FOL
Controller
The operation of the A/C system is controlled by
the switches and the lever on the control head. The
compressor clutch and blower are connected electri-
cally to the control head by a wiring harness. The
blower circuit is open in the off mode and air flow is
provided by the four blower speeds available in the
remaining modes. Cooled and dehumidified air is
available in the max, normal, bi-level and defrost
modes.
Temperature is controlled by the position of the
temperature lever on the control head. A cable con-
nects this lever to the temperature door which controls
air flow through the heater core. As the temperature
lever is moved through its range of travel, a sliding
clip on the cable at the temperature valve connection
should assume a position assuring that the temperature
door will seat in both extreme positions. Temperature
door position is independent of mode selection. The
temperature cable attaches to the right side of the air
conditioning module. The temperature door on some
models is controlled electrically, thereby eliminating
the need for the temperature cable.
The electric engine cooling fan on some cars is
not part of the
A/C system; however, the fan is
operational any time the
A/C control is in Max.,
Norm, or Bi-Level modes. Some models provide for
engine cooling fan operation when the controller is in
the defrost mode. This added feature is part of the
A/C
controller function and is aimed at preventing exces-
sive compressor head temperatures. It also allows the
A/C system to function more efficiently. On some
models during road speed (above
35 mph) conditions
when air flow through the condenser coil is adequate
for efficient cooling, the engine cooling fan will be
turned off. The operation of the cooling fan is con-
trolled by the ECM through the cooling fan relay.
Complete wiring diagrams and diagnosis for the
AIC Electrical System are in Section 8A. Section 8A
also contains additional diagnostic information
regarding air flows and vacuum logic.
Vacuum Lines
Vacuum lines are molded to a connector which
is attached to a vacuum control switch on the control
head assembly.
In case of leakage or hose collapse, it will not be
necessary to replace the entire harness assembly.
Replacement can be made by cutting the hose and
inserting a plastic connector. If an entire hose must be
replaced, cut all hoses off at the connector and then
attach hoses directly to the control head vacuum
switch. (NOTE: The Fiero uses an electric motor to
control mode selection. Therefore, it will not have a
vacuum harness.
)
Vacuum Tank
During heavy acceleration, the vacuum supply
from the carburetor drops. A check valve in the vac-
uum tank maintains vacuum so that, under load condi-
tions, vacuum will be available for continuous use.
REWVS AND SWITCHES
High-Pressure Compresssr Gut-OFF Switch
The high-side, high-pressure cut-off switch in
the rear head of the compressor is a protective device
intended to prevent excessive compressor head pres-
sures and reduce the chance of refrigerant escape
through a safety relief valve. Normally closed, this
switch will open the circuit at a high-side pressure of
approximately 2700
kPa (430 psi 9 20 psi) and
reclose the circuit at approximately 1379 kPa (200 psi
9 50 psi).
Lsw-Pressure Cut-On Switch
Compressor protection is provided on some cars
by a low-pressure cut-off switch which will open in
the event of a low-charge condition. This switch can
be located in the liquid line or in the rear head of the
compressor. This switch will also keep the compres-
sor from running during cold weather.
Pressure eyesing Switch
The refrigeration cycle (on and off operation of
the compressor) is controlled by a switch which
senses the low-side pressure as an indicator of evapo-
rator temperature. The pressure cycling switch is the
freeze protection device in the system and senses
refrigerant pressure on the suction side of the system.
This switch is located on a standard Schrader-type
valve low-side fitting. This switch also provides com-
pressor cut-off during cold weather.
Additional compressor protection results from
the operating characteristics of the low-side pressure
cycling system. If a massive discharge occurs or the
orifice tube becomes plugged, low-side pressures
could be insufficient to close the contacts of the pres-
sure switch. In the event of a low charge, insufficient
cooling accompanied by rapid compressor clutch
cycling will be noticed at high air temperatures.

AIR CONDITIONING 113-5
DIAGNOSIS
TESTING THE REFRIGERANT SYSEEM
If a malfunction in the refrigerant system is sus-
pected, check the following:
1. Check outer surfaces of radiator and condenser
cores to be sure air flow is not blocked by dirt,
leaves or other foreign material. Be sure to
check between the condenser and radiator as
well as the outer surfaces.
2. Restrictions or kinks in the condenser core,
hoses, tubes, etc.
3. Blower fan operation (see Section 8A).
4. Check all air ducts for leaks or restrictions. Low
air flow rate may indicate a restricted evaporator
core.
5. Compressor clutch slippage.
6. Improper drive belt tension.
7. See C.C.O.T. AIC system diagnostic
procedures.
InsufFicient Cooling "Quick-Check"
Procedure
The following "HAND-FEEL" procedure can
be used to approximate whether or not the
AIC system
has the proper charge of Refrigerant- 12 (providing air
temperature is above
2 1°C [70°F])on most models. This check can
be made in a matter of minutes and
may simplify system diagnosis by pinpointing the
problem to the amount of
W- 12 charge in the system or
by eliminating low charge possibility from the overall
checkout.
1. Engine must be
warm(CH0KE OPEN and OFF
FAST IDLE SPEED CAM) and at normal idle
speed.
2. Hood and body doors open.
3. Selector (mode) button set at "NORM."
4. Temperature lever at full COLD.
5. Blower on "HI."
6. "Hand-Feel" temperature of evaporator inlet
pipe after orifice, and accumulator surface, with
compressor engaged.
BOTH SAME TEMPERATURE AND
BOTH SAME DEGREE COOLER
THAN AMBIENT
- Proper condition:
check for other problems; (see Testing the
Refrigerant System).
@ Leak check. If leak found, dis-
charge and repair as required. Evac-
uate and recharge.
e If no leak found, see A/C System
Diagnostic Procedures.
EVAPORATOR
'MODE POSITION
INDICATED
BY (
Figure 3 AIC Air Flow --- Typical

1B-8 AIR CONDITIONING
INSUFFICIENT COQblNG "CHART A
A/C FUSE AND/OR GAGE FUSE.
OR DISCONNECTED
AlC WIRE CONNECTOR.
. CHECK BLOWER FOR FAN OPERATION.
. ENGINE COOLING FAN OPERATION (FAN OPERATES IN ALL A/C MODES AS FOLLOWS:
A. DISCONNECT ENGINE COOLANT TEMPERATURE FAN SWITCH.
8. WITH IGNITION ON AND ENGINE NOT RUNNING, SET A/C CONTROL TO A/C MODE.
C. ENGINE COOLING FAN SHOULD RUN.
D. RECONNECT ENGINE COOLANT TEMPERATURE FAN SWITCH.
REPLACE COMPRES-
SOR ASSEMBLY. RE-
PLACE ORIFICE. EVA-
CUATE AND CHARGE. AS
REQUIRED
AND 'HIGH' BLOWER.
T
AUXIL I ARY FAN IN T OF VEHICLE.
I OFF ALL THE TIME I
RESTRICTION IN HIGH
SIDE OF SYSTEM.
VISUALLY CHECK FOR
FROST SPOT TO LOCATE
RESTRICTION. REPAIR.
Figure
8 C.C.O.T. NC System Insufficient Cooling Diagnostic Procedure (1 of 4)

AIR CONDITIONING 1B-17
If prescribed vacuum cannot be reached, close
vacuum control valve, shut off pump and look
for a leak at connections or pump.
3. When gauge reaches prescribed vacuum, the
system is fully evacuated. Close the high-side
gauge set valve and turn off the vacuum pump.
4. Watch low-side gauge to be sure vacuum holds
for five (5) minutes. If vacuum is held, discon-
nect vacuum hose at gauge set and then proceed
to charging.
5. If vacuum does not hold for five (5) minutes,
charge system with
420ml(1/2 pound) Refriger-
ant-12 and leak check. Discharge system again
and repair leak as necessary. Repeat evacuation
procedure.
To Begin Charging of the NC System
1. Start engine and set A/C mode control button on
"OFF. "
2. With the Refrigerant-12 drum or 420ml (14
ounce)
can(s) inverted, open R-12 source
valve(s) and allow 480ml (1 pound) or one
420m1 (14 02.) can of liquid R-12 to flow into
system through low-side service fitting.
3. As soon as 480ml (1 lb.) or one 420ml (14 oz.)
can of R-12 has been added to system, immedi-
ately engage the compressor by setting the
A/C
control button to NORM and blower speed on
HI, to draw in the remainder of the R-12 charge.
See specifications for total R-12 charge. The
charging operation can be sped up by using
a large volume fan to pass air over the con-
denser. If condenser temperature is maintained
below charging cylinder temperature,
Refriger-
ant-12 will enter the system more rapidly.
4. Turn off
R-12 source valve and run engine for
30 seconds to clear lines and gauges.
5. With the engine running, remove the charging
low-side hose adapter from the accumulator ser-
vice fitting. Unscrew rapidly to avoid excess
R-12 escape from system.
CAUTION: NEVER REMOVE A GAGE
LINE FROM ITS ADAPEER WHEN LINE
IS CONNECTED TO A/G SYSTEM.
ALWAYS REMOVE
THE LINE ADAPTER
FROM THE
SERVICE F1miNG TO DIS-
CONNECT A LINE. DO
NOT REMOVE
CHARGING
HOSE AT GAGE SET WHILE
ATTACHED TO ACGUMULBTOR. "THIS
WILL RESULT IN COMPLETE DIS-
CHARGE OF SYSTEM DUE TO THE
DEPRESSED SCHRADER VALVE IN
SERVICE LOW-SIDE
F17$TING, AND MAY
CAUSE PERSONAL
INJURY DUE TO
ESCAPING REFRIGERANT-72;.
6. Replace protective cap on accumulator fitting.
7. Turn engine off.
8. Leak check system with electronic leak detector
5-29547 or equivalent (see Diagnosis).
9. Start engine.
10. With system fully charged and leak-checked,
continue to operate system performance.
THIS HI-PRESS. VALVE IS
EVACUATION
ACCUMULATOR
ISPENSING UNIT
30 LB. DRUM HAS
OWN OPENER-VALVE
WARNING: MAKE SURE OUTLET VALVE
ON OPENER IS CLOSED (CLOCKWISE)
R-12 CQNTAINER.
OPEN AND INVERTED
DURING CHARGING
EVACUATION
Figure 16 Charging the System With Disposable Can or Drum

AIR CONDITIONING 18-21
8. Disconnect blower motor
and blower resistor
electrical connection.
9. Remove hi-blower relay connector from evapo-
rator case.
10. Carefully pull
cowl grommet from cowl and pull
wiring
hmess into engine compartment.
Install or Connect
1. Reverse removal procedure to
reinstall. When
reinstalling controller, install lower right screw
first to align controller.
ACNENTILATIONIDEFROSVER DUCTS
See section 8C for removal.
HEATER CORE
Remove or Disconnect
1. Negative battery cable.
2. Drain cooling system.
3. Remove heater inlet and outlet hoses
from
heater core.
4. Remove right lower hush panel (see Section
8C).
5. Remove right
lower I.P. trim panel (see Section
8C) .
6. Remove lower right I.P. carrier to cowl screw.
7. Remove ECM attaching screws and move to the
side.
8. Remove four
(4) heater case cover screws.
Upper left screw may be reached with a long
318 ' socket extension through the I.P. openings
exposed by removal of the lower right I.P. trim
panel. Carefully lift the lower right corner of the
I.P. to align socket extension.
9. Remove heater case cover.
10. Remove core support plate
and baffle screws.
- -
11. Remove
heater core, support plate and baffle
from case.
Install or Conned
1. Reverse removal procedure to reinstall. Restore
all seals
and/or sealant disturbed during removal
procedure.
2. Refill cooling system and check for leaks.
LOWER (FLOOR) )-IEA"FEB$OU"fET
Remove or Disconnect
1. Console. (See Section 8C.)
2. L.H. and R.H. hush panels.
3. Two (2) floor outlet retaining screws.
4. Floor outlet from core case.
lnstall or Connect
1. Floor outlet to core case.
2. Two (2) floor outlet retaining screws.
3. L.H. and R.H. hush panels.
4. Console.
HEATER MODULE (CASE)
Remove or Disconnect
1. Disconnect negative battery cable.
2. Drain cooling system.
3. Remove hush panels and instrument panel car-
rier (see Section
8C).
4. Remove lower heater outlets.
5. Disconnect control cables and vacuum hoses at
module and controller.
6. Remove heater core.
7. Remove two (2) interior screws and one (I)
exterior nut holding case to cowl.
8. Remove evaporator core.
9. Remove screw holding case to cowl from engine
compartment side.
10. Remove case (module).
11. Transfer usable parts to new case (module).
lnstall or Conned
1. Reverse removal procedure to reinstall.
2. Refill coolant system.
3. Recharge
A/C system.
4. Inspect A/C and cooling system for leaks.
NC PRESSURE CYCLING SWITCH
Do not discharge A/C system. Pressure cycling
switch is mounted on
a Schrader-type valve.
Remove or Disconnect
1. Disconnect switch electrical connection.
2. Remove switch.
Install or Connect
1. Reverse removal procedure to reinstall. Tighten
switch to
4-5.5 N*m (35-49 in. lb.).
Ale CONTROL VACUUM TANK
Remove or Disconnect
1 . Disconnect vacuum hoses.
2. Remove vacuum
tank attaching screws, remove
tank.
lndall or Connect
1. Reverse removal procedure to
reinstall.

BUMPERS 28-1
SECTION 2B
BUMPERS
NOTICE: These fasteners are important attaching parts in that they could affect the performance of vital parts and
systems,
andlor could result in major repair expense. They must be replaced with one of the same part number or with an
equivalent
part if replacement becomes necessary. Do not use a replacement part of lesser quality or substitute design.
Torque values must be used as specified during reassembly to assure proper retention of all parts. There is to be no
welding as it may result in extensive damage and weakening of the metal.
NOTICE: The anti-theft label on some major sheet metal, engines, and transmissions must be masked prior to
painting, rustproofing, undercoating, etc. The mask MUST be removed following the above operations. Failure to keep
the label clean and readable may result in liability for violation of Federal Vehicle Theft Prevention Standard, and subject
the vehicle owner to possible suspicion that the part was stolen.
CONTENTS
General Description ................................ 2B-1 On-Vehicle Service ..................................... 2B-4
........................................... ..................... Service Procedures .. ........... 2B- 1 Specifications 2B-5
GENERAL DESCRIPWIBN
The bumpers on all Pontiac automobiles are remover.
Install new tape (double-coated neoprene
designed so that the vehicle can withstand a collision foam type)
to the back side of the rub strip.
into a fixed barrier at
5 mph. After absorbing the
energy of a collision, the bumpers restore themselves After
rub strip is installed, roll along entire
to their original position. surface with a roller
in order to insure a good bond.
The front and rear bumper fascias are made of
urethane. Urethane will withstand minor impact and
return to its original shape. Some front bumper fascias
are integral with the front end panel.
Some models use both steel and aluminum
bumper reinforcements. Usage is based on
EPA weight
class requirements.
BUMPER FASCIA RUB STRIPS
Some front and rear fascia rub strips are made of
a shiny plastic material. If a rub strip of this type loses
its lustre, the original shine can be restored by using
GM Plastic Cleaner or its equivalent. Follow directions
on the label.
SERVICE PROCEDURES
RUB STRIPS
Remove and Replace
Some plastic rub strips have an adhesive tape
backing (similar to a body side molding) and some have
studs or retaining tabs. In order to properly remove the
adhesive tape and avoid paint damage to the fascia, use
either a release agent or a heat lamp to soften the bond
of the adhesive tape to the fascia. In some cases, it will
be necessary to replace the rub strip with a new rub
strip instead of reusing the old one.
If the old rub strip is salvagable, remove all tape
from the back side of the rub strip as previously
described. Wipe strip clean with a wax and adhesive
FRONT BUMPER FASCIA (FRONT END PANEL)
Removal
Place a jack stand under fascia assembly before
removing bolts to prevent it from dropping down when
fascia attaching bolts are removed. Fascia will pivot on
the opposite end when one end is disconnected. Do not
rotate energy absorber any more than necessary to
align mounting holes.
1. Remove fascia attaching bolts and fascia to
fender attaching screws on right and left side, and
remove fascia and spacers.
2. If energy absorber is to be replaced, remove the
bolts and nuts from the front of the unit and the
nut from the stud at the rear.
Installation
1. Install energy absorber if removed.
2. Support fascia during installation to prevent
rotation of energy absorbers.
3. Install spacers and bolts at fascia to energy
absorber brackets.
4. Install fascia to fender attaching screws.
5. Check for proper clearance.
6. If adjustment is required to align fascia, loosen
energy absorber mounting bolts and position as
required (holes are slotted). Adjustment side to
side can be made by loosening fascia bracket
bolts. Torque all bolts and nuts. (See
Specifications.)

STEERING, SUSPENSION, VIBES AND WHEELS DIAGNOSIS 3-3
Steering Wheel Kick-Back (Power)
Inspect
e Air in system
e Loose steering gear mounting
e Joints from column to steering gear loose or worn
e Tie rod ends loose
Worn or missing check valve
(800 series)
e Wheel bearings worn
e See "Too Much Play In Steering" for other
possible causes.
Steering Wheel Surges Or Jerks (Power)
Inspect
Hydraulic system - Make pressure test with gage
J 5176-D or
J 25323
e Sluggish steering gear valve
Loose pump drive belt
Cupped Tires
Inspect
Front-wheel or rear-wheel alignment
e Strut dampeners or shock absorbers weak
e Wheel bearing worn
e Excessive tire or wheel runout
e Worn ball joint
a Loose steering gear adjustment
POWER RECIRCULATING BALL
SEERING GEAR DIAGNOSIS
Hissing Noise
There is some noise in all power steering systems.
One of the most common is a hissing sound when the
steering wheel is turned and the car is not moving. This
noise will be most evident when turning the wheel
while the brakes are applied. There is no relationship
between this noise and steering performance. Do not
replace the valve unless the "hissing" noise is extremely
objectionable. A replacement valve will also have a
slight noise, and is not always a cure for the condition.
Check that the intermediate shaft joints are not loose.
Rattle or Chucking Noise
Inspect -
Pressure hose grounding out
e Tie rod ends loose
e Steering gear attachment loose
a Loose pitman shaft "over-center" adjustment.
A slight rattle may occur on turns because of
increased clearance off the "high point". This is
normal and clearance must not be reduced below
specified limits to eliminate this slight rattle.
Poor Return of Steering Wheel to Center
Front-wheel alignment
Wheel bearing worn
Tie rod end binding
Ball joint binding
Steering wheel rubbing against turn signal
housing
Steering gear adjustments
Tight or frozen intermediate steering shaft
Sticky or plugged spool valve
Momentary Increase in Effort Whsn Turning
Wheel Fast to Right or Left
Inspect
High internal leakage
Steering Wheel Surges or Jerks When Turning
With
Engine Running Especially During Parking
ln8pe~t
e Insufficient pump pressure
Sticky flow control valve
Excessive Wheel Kickback or Loose Steering
Air in system
Steering gear attachment loose
Tie rod ends loose
Wheel bearings worn
Steering gear flexible coupling loose on shaft or
rubber disc mounting nuts loose
Loose thrust bearing preload adjustment
Excessive "over-center" lash
Worn pressure port check valve
Hard Steering or Lack of Assist
(Especially During Parking)
-
Brakes applied while turning steering wheel
Intermediate shaft damaged or worn
e Sticky flow control valve
Insufficient pump pressure
Excessive internal pump leakage
Excessive internal steering gear leakage
STEERING LINKAGE DIAGNOSIS
Excessive Play or Looseness in Steering Systern
inspect
r, Worn upper ball joints
e Steering gear worm bearings loosely adjusted