1988 PONTIAC FIERO Service Repair Manual

0.4-14 GENERAL INFORMATION
SERVICE PARE SlDENTlFlGATlON LABEL
The Service Parts Identification Label provides identifi- fixed to the inside of each passenger car vehicle at the
cation of vehicle equipment to assist in servicing and assembly plant.
determining replacement parts, Included on this label
will be regular production options
(RPO's) as well as For
additional information on the Service Parts Identifi-
standard and mandatory options. The label will be af- cation
Label, see a GM Parts Catalog.
VEHICLE ---f IDENTIFICATION
NUMBER lGlAZ3799ER157148 1JD69
ARL A02 A65 BGY B9A B9K C60 Dl0 D35 E5Z E6E E9Z FLT GU1 JM7
<19
KG4 LC3 MX1 M31 NA5 NB1 OMX VK3 VC2 VY1 VY4 V73 Y19 ZJ7
GBJ 62L 62U 67D 671 679 7BJ 8HJ 9HJ
BBPBBBBPPB EXAMPLE -
DIS. LACQUER WA-L8240 U8240 A4721
i
BODY TYPE STYLE
OPTION CONTENT
PAINT
TECHNOLO(IY SOLUTION LACOUEH DlSPEHSlON LACOUEH
HIGH SOLIDS EN4MEL
VINYL FOP CCIl.Oli IlF AI'I'LICAHLZI
\VA CERBORNE ENAI.ICL I'AINT LOULS APd[J LOLATIONS I BASECOAT CLCAl3C04T L LfJIVEIi L:C)UY COLOII 1lilP.1 U UPI'CH f!O[IY (,OLCJII ~,lJP.ll~lPl/~ llO'J', A hllI1ULf L!O[)Y OII ACCCNT COLOF? ISTHIPINO CTC. I
LABEL LOCATION
Fig. OA-16 Service Parts Idcnt~frcation Label

MAINTENANCE AND LUBRICATION OB-1
SECTION OB
NTENANCE AND LUBR
CONTENTS
Maintenance Schedule, Gasoline .............................................. OB-l
Maintenance Schedules I and 11 .............................................. OB-2
Owner Inspections
......................................................... OB-3
Recommended Fluids and Lubricants ......................................... OB-6
PASSENGER CAR MAINTENANCE SCHEDULE
VEHICLES
WITH GASOLINE ENGINE
NORMAL CAR USE ITEM 4
The maintenance services contained in Schedules I Carburetor or Throttle Body Mounting Bolt
and 11 are based on the assumption that your car will be Torque* used as designed:
Check torque of mounting bolts and/or nuts. @ To carry passengers and cargo within the limits
shown on the Tire Placard located on the edge of the ITEM 5 driver's door.
@ On reasonable road surfaces within legal driving Engine Idle Speed Adjustment*
limits. (Engines
without Idle Speed Control or Idle Air
Control) - Adjust to specifications shown on the under- @ On unleaded gasoline.
hood label. If no specifications are shown on the label, no
adjustment is necessary. Calibrated test equipment must
EXPLANATION OF SCHEDULED MAINTENANCE be used. SERVICES
The services listed in Maintenance Scheduies I and ITEM 6
11 are further explained below. When the following main- ~i~~ and wheel aotation tenance services are performed, make sure all parts are
replaced and all necessary repairs are done before driving To equalize wear and obtain maximum tire life,
your car. Be sure to use the proper fluid and lubricants as rotate in accordance with patterns shown in Owner's
shown in Figure OB-2. Manual.
ITEM 1
Engine Oil and Oil Filter Change*
ALWAYS USE SFICC OR SF/CD ENERGY CON-
SERVING OILS OF PROPER VISCOSITY
- Also.
always change oil and filter as soon as possible after
driving in a dust storm. See your Owner's Manual for
further details.
ITEM 2
Chassis Lubrication
Lubricate all grease fittings in suspension and steer-
ing linkage. Lubricate
transmissionltransaxle shift
linkage, parking brake cable guides, underbody contact
points and linkage. Also lubricate clutch cross shaft lever
every
30,000 miles (50 000 km) on rear-wheel-drive cars
only.
ITEM 3
Carburetor Choke and Hoses*
If your car is equipped with a carburetor, verify that
choke and vacuum break work properly and are within
specifications. Correct any binding caused by damage or
gum on the choke shaft. Inspect hoses for proper hookup,
cracks, chafing or decay. Correct as necessary.
Vacuum or A.I.R. Pump Drive Belt Inspection*
When a separate belt is used to drive the vacuum or
A.I.R.
pump, inspect it for cracks, fraying, wear and
proper tension. Adjust or replace as needed.
ITEM 8
Cooling System Service*
Drain, flush and refill system with new coolant. See
your Owner's Manual
for further details.
ITEM 9
Wheel Bearing Repack (Rear-Wheel-Drive Cars
Only Except Corvette)
Clean and repack front wheel bearings at each brake
relining or 15,000 miles
(25 000 km), whichever comes
first, when car is used in such service as police, taxi or
door-to-door delivery. If you do not use your car in such
service, clean and repack bearings at each brake relining
or 30,000 miles
(50 000 km), whichever comes first.
Corvette models do not require wheel bearing repack.

OB-2 MAINTENANCE AND LUBRICATION
Select and follow Schedule I or Schedule I1 based on how you use your car:
SCHEDULE I
Follow Schedule I if your car is mainly operated under one or moreof the following Idling andlor low
speed operation in stop-and-go traffic.
conditions: Towing a trailer.
@ When most trips are less than 4 miles (6 kilometers).
Operating in dusty areas.
When most trips are less than 10 miles (16 kilometers) and outside temperatures
Schedule I should also be followed if the car is used for delivery service,
remain below freezing.
police, taxi or other commercial applications.
TO BE SERVICED
Every
30.000 miles I50 000 km)
Every 30,000 miles I50 000 km) or 36 months
Every
30,000 miles 150 000 km)
SCHEDULE ll
Follow Schedule II only if none of the driving conditions specified in Schedule I apply.
TO BE SERVICED
At
7 500 miles 12 500 km on1
FOOTNOTES:
I
*An Emission Control Service ttThe U.S. Environmental Protection Agency has determined that the failure to perform this
maintenance item will not nullifv the emission warrantv or limit recall liabilitv orior to the
completion of vehicle useful life. General Motors, however, urges that all recommended main-
tenance services be performed at the indicated intervals and the maintenance be recorded in
section C of the owner's
ma~ntenance schedule.
Figure OB-1 Maintenance Schedules I and I1 - Gasoline Vehicles

F CARLINE
ITEM 10
TransmissionRransaxle Service
The manual transmission or transaxle fluid does not
require changing. (Corvette only.) Change fluid in over-
drive unit every 30,000 miles (50 000 km).
For automatic transmissions or transaxles, change
both the fluid and filter every 15,000 miles (25 000 km) if
the car is mainly driven under one or more of these
conditions:
@ In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
@ In hilly or mountainous terrain.
@ Frequent trailer pulling.
@ Uses such as found in taxi, police car or delivery
service.
If you do not use your car under any of these condi-
tions, change both the fluid and filter every 100,000 miles
(160 000 km). See you Owner's Manual for further
details.
ITEM 11
Spark Plug Service*
Replace spark plugs with type listed in your Owner's
Manual.
ITEM 12
Spark Plug Wire Inspection*
Clean wires and inspect for burns, cracks or other dam-
age. Check the wire boot fit at distributor and at spark plugs.
Replace wires as needed.
ITEM 13
Positive Crankcase Ventilation (PCV) Valve
Inspection*
Inspect valve for proper function. Replace valve if
necessary as well as any worn, plugged or collapsed
hoses.
ITEM 14
EGR System Service*
Conduct EGR System Service as referenced in the
EGR System Chart shown in the appropriate 6E Section.
Also, refer to your GM maintenance schedule booklet for
specific applications.
ITEM 15
Air Cleaner and PCV Filter Replacement*
On 1.6 and 2.0 liter engines, replace every 50,000
miles (80 000 km). On all other engines, replace every
30,000 miles (50 000 km). Replace more often under
dusty conditions. Ask your dealer for the proper replace-
ment interval for your driving conditions.
MAINTENANCE AND LUBRICATION 08-3
ITEM 16
Engine Timing Check*
Adjust timing to underhood label specifications. If
no specifications are shown, no adjustment is needed.
ITEM 17
Fuel Tank, Cap and Lines Inspection*
Inspect fuel tank, cap and lines (including fuel rails
and injection assembly, if so equipped) for damage or
leaks. Inspect fuel cap gasket for an even filler neck
imprint or any damage. Replace parts as needed.
ITEM 18
Thermostatically Controlled Air Cleaner
Inspection*
If your car is equipped, inspect all hoses and ducts
for proper hookup. Make sure valve works properly.
OWNER INSPECTIONS AND SERVICES
Listed below are inspections and services which
should be made by either you or a qualified technician at
the intervals shown to help ensure proper safety, emission
performance and dependability of your car. Take any
problems promptly to your dealer or another qualified
technician for service advice. Whenever repairs are neces-
sary, have them completed at once. For your safety and
that of others, any safety-related parts that could have
been damaged in an accident should be inspected and all
needed repairs should be done before operating your car.
Be sure to use the proper fluids and lubricants as shown in
Figure OB-2.
WHILE OPERATING YOUR VEHICLE
Automatic transmissionltransaxle shift indi-
cator operation - Make sure the indicator points to the
gear chosen.
Horn operation - Blow the horn occasionally to
make sure it works. Check all button locations.
I
Brake system operation -- Be alert to abnormal
sounds, increased brake pedal travel or repeated pulling to
one side when braking. Also, if a brake warning light
comes on or flashes, or the anti-lock warning light (if
equipped) comes on or remains on, something may be
wrong with part of the brake system. Have it inspected and
repaired at once.
Exhaust system operation - Be alert to any
changes in the sound of the system or any smell of fumes.
These are signs the system may be leaking or overheating.
.
Have it inspected and repaired at once. Also see "Engine
Exhaust Gas Caution (Carbon Monoxide)" and "Catalytic
Converter" in your Owner's Manual.
*An Emission Control Service

OB-4 MAINTENANCE AND LUBRICATION
Tire and wheel operation - Be alert to a vibra-
tion of the steering wheel or seat at normal highway
speeds. This may mean a wheel balance is needed. Also, a
pull right or left on a straight, level road may show the
need for
a tire pressure adjustment or wheel alignment.
Steering system operation - Be alert to
changes in steering action. An inspection is needed when
the steering wheel is harder to turn or has too much free
play or if unusual sounds are noted when turning or
parking.
Headlight aim operation - Take note of light
pattern occasionally. If beam aim doesn't look right,
headlights should be adjusted.
AT EACH FUEL FILL
Engine oil level check - Check engine oil level
and add if necessary. See your Owner's
Manual for further
details.
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Engine coolant level and condition - Check
engine coolant level in coolant reservoir tank and add if
necessary. Replace if dirty or rusty. See your Owner's
Manual for further details.
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Windshield washer fluid level check -- Check
washer fluid level in container and add if necessary.
Hood latch operation - When opening hood on
cars equipped with hoods that open from the front, note
the operation of secondary latch. It should keep hood from
opening all the way when primary latch is released. Make
sure that hood closes firmly.
AT LEAST MONTI-ILY
Tire and wheel inspection and pressure
check--
Check tires for abnormal wear or damage. Also,
check for damaged wheels. Keep pressures as shown on
Tire Placard on the driver's door (include spare unless it is
a stowaway). Pressure should b\: checked when tires are
"cold". See "Tires" in Owner's Manual for further
infomation.
Light operation check - Check operation of
license plate light, side-marker lights, headlights includ-
ing high beams, parking lights, taillights, brake lights.
turn signals, backup lights, instrument panel and interior
lights and hazard warning flashers.
Fluid leak check - After the car has been parked
for a while, inspect the surface beneath the car for water,
oil, fuel or other fluids. Water dripping from the air
conditioning system after use is normal. If you notice fuel
leaks or fumes, the cause should be found and corrected at
once.
AT LEAST TWICE A YEAR (FOR EXAMPLE,
EVERY SPRING AND FALL)
Power steering pump fluid level check --
Check power steering pump fluid level in accordance with
Owner's Manual instructions and keep at proper level.
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Brake master cylinder reservoir fluid level
check ---- Check fluid and keep at proper level. Note: It is
normal for the brake fluid level to go down slightly as the
brake pads wear
- so be sure to keep reservoir filled.
NOTICE: A large loss in this system may indicate a
problem. Have
it inspected and repaired at once.
Clutch system service --- manual transmis-
sionltransaxle --- For cars equipped with hydraulic
clutch system, check the reservoir fluid level and add fluid
as required. All others, check clutch pedal free travel and
adjust as necessary. See your Owner's Manual for further
details.
~
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Weatherstrip Lubrication - Clean surface and
then apply a thin film of silicone grease with a clean cloth.
EACH TIME OIL IS CHANGED
Automatic and manual transmissionltrans-
axle fluid level check - Check transmission/transaxle
fluid level and add as required. (Corvette only) if equipped
with manual transmission
- check fluid in the overdrive
unit and add as required.
NOTICE: A large loss in this system may indicate a
problem. Have
it inspected and repaired at once.
Brake systems inspection - For convenience,
the following should be done when wheels are removed
for rotation: Inspect lines and hoses for proper hookup,
binding, leaks, cracks, chafing, etc. Inspect disc brake
pads for wear and rotors for surface condition. Also in-
spect drum brake linings for wear and cracks. Inspect
other brake parts, including drums, wheel cylinders, park-
ing brake, etc. at the same time. Check parking brake
adjustment.
INSPECT BRAKES MORE OFTEN IF DRIVING
HABITS OR CONDITIONS RESULT IN FREQUENT
BRAKING.
Steering, suspension and front drive axle
boot and seal inspection
- Inspect front and rear
suspension and steering system for damaged, loose or
missing parts, signs of wear or lack of lubrication. Inspect
power steering lines and hoses for proper hookup, bind-
ing, leaks, cracks, chafing, etc. (On cars equipped with
manual steering gear, check for seal leakage.) On
front-
wheel-drive cars, clean then inspect drive axle boot seals
for damage, tears or leakage. Replace seals if necessary.
Exhaust system inspection - Inspect complete
system. Inspect body near the exhaust system. Look for
broken, damaged, missing or out-of-position parts as well
as open seams, holes, loose connections or other condi-
tions which could cause a heat buildup in the tloor pan or
could let exhaust fumes seep into the trunk or passenger
compartment.

MAINTENANCE AND LUBRICATION OB-5
Throttle linkage inspection -- Inspect for inter-
ference, binding, damaged or missing parts.
Engine drive belts inspection - Inspect all
belts for cracks, fraying and wear. Adjust or replace as
needed.
Rear axle service (if equipped) - Check gear
lubricant level and add if needed. For cars equipped with a
limited slip rear axle, fluid does not require changing
(except Caprice and Corvette
- change fluid and required
additive at first
7,500 miles (12 500 km). See your
Owner's Manual or "Recommended Fluids
& Lubricants
Chart" in this section.
IF YOU USE YOUR GAR TO PULL A TRAILER,
CHANGE GEAR LUBRICANT EVERY 7,500 MILES
(12 500 KM).
NOTICE: A large loss in this system may indicate a
problem. Have it inspected and repaired at once.
Power antenna - Clean and then lubricate power
antenna mast. The proper lubricant as shown in Figure
OB-2 should be used.
AT LEAST ONCE A YEAR
Lap and shoulder belts condition and opera-
tion
- Inspect belt system, including webbing, buckles,
latch plates, retractors, guide loops and anchors.
Moveable head restraint operation - On cars
with moveable restraints, make sure restraints stay in the
desired position. (See adjustment instructions in your
Owner's Manual.)
Seatback latch and recliner operation on
cars equipped
with recliner seat --- Be sure seat-
backs latch on those cars with folding seats using mechan-
ical latches. Make sure the recliner is holding by pushing
and pulling on the top of the
seatback while it is reclined.
See your Owner's Manual for seat operating information.
Spare tire and jack storage- Be alert to rattles
in rear of car. Make sure the space tire, all jacking equip-
ment, any tire inflator and any covers or doors are securely
stowed at all times. Oil jack ratchet or screw mechanism
after each use.
Key lock service - Lubricate key lock cylinder at
least annually.
Body lubrication service - Lubricate all body
door hinges including the tailgate or hatchback lid (if
equipped). Also lubricate the body hood, fuel door and
rear compartment hinges and latches including interior
glove box and counsel doors, and any folding seat
hardware.
"Fansmissionltransaxle neutral or clutch
starl switch operation
CAUnON: Before pedorming the follow-
ing safety switch check, be sure to have
enough room around the car. Then, firmly
apply both the parking brake (see your
Owner's Manual for procedure) and the
regular brakes. Do not use the accelerator pedal.
If the engine
starls, be ready to turn
off the ignition promptly. Take these pre-
cautions because the car could move
without warning and possibly cause per-
sonal injury or properly damage. On auto-
matic transmissionltransaxle cars, try to
starl the engine in each gear. The starler
should crank only in "Park" or "Neutral."
On manual transmissionltransaxle cars,
place the
shiR lever in "Neutral," push the
clutch halfway and try to starl. The starler
should crank only when the clutch is fully
depressed.
Steering column lock operation
- While
parked, try to turn key to "Lock" in each gear range. The
key should turn to "Lock" only when gear is in "Park" on
automatic or "Reverse" on manual
transmissionltransax-
le. On cars with key release lever, try to turn key toULock"
without depressing the lever. The key should turn to
"Lock" only with the key lever depressed. On all vehicles,
the key should come out only in "Lock."
Parking brake and transmissionltransaxle
"Park" mechanism operation
CAUT1ON:Before checking the holding
ability of the parking brake and automatic
transmissionltransaxle "Park" mecha-
nism, park on a fairly steep hill with
enough room for movement in the down-
hill direction. To reduce the risk of person-
al injury or property damage, be prepared
to apply the regular brakes promptly if the
car begins to move.
To check the parking brake, with the engine running and
transmission/transaxle in "Neutral." slowly remove foot
pressure from the regular brake pedal (until the car is held
by only the parking brake).
To check the automatic transmissionltransaxle "Park"
mechanism holding ability, release all brakes after shift-
ing the transmissionltransaxle to "Park."
ljnderbody flushing - At least every spring,
tlush from the underbody with plain water any corrosive
materials used for ice and snow removal and dust control.
Take care to thoroughly clean any areas where mud and
other debris can collect.
Sediment packed in closed areas
of the vehicle should be loosened before being flushed.
Engine cooling system service - Inspect
coolant and freeze protection. If dirty or rusty, drain, flush
and refill with new coolant. Keep coolant
at the proper
mixture as specified in your Owner's Manual. This pro-
vides proper freeze protection. corrosion inhibitor level
and engine operating temperature. Inspect hoses and re-
place if cracked. swollen or deteriorated. Tighten hose
clamps. Clean outside of radiator and air conditioning
condensor. Wash radiator filler cap and neck.
To help
ensure proper operation. a pressure test of both the cooling
system and cap is also recommended. (See maintenance
schedule charts in Figure
OB-l for the recommended
coolant change interval.)

NOTE: Fluids and lubricants identified below by name, part number or specification may be obtained from your GM dealer.
Figure 00-2 Recommended Fluids and Lubricants
USAGE
Engine
Oil
Engine Coolant
Brake and
Hydraul~c Clutch Systems
Parking Brake Cables
Power Steering System
Manual
Steerlng Gear (reclrculat~ng ball)
Automatic
Transrn~ssionRransaxle and 5 Speed Manual Transm~ss~ons
Manual Transm~ssion (rear-wheel-drive) 4 Speed
Manual
Transm~ss~onRransaxle Shin Linkage
Key Lock Cylinders
Automatic Transmlss~onfrransaxle Shlft Llnkage
Clutch Llnkage Plvot Po~nts
Floor Sh~n L~nkage
Power Antenna Mast (3-mast sect~on-type only)
Chass~s Lubr~cation
Standard D~fferent~al Rear Axle
L~m~ted-Sl~p D~flerent~al Rear Axle
W~ndsh~eld.Washer Solvent
Hood Latch Assembly
a)
Plvots and Sprlng Anchor
b) Release Pawl
Front Wheel Bearings
(rearqwheel-drive)
Hood and door hlnges, statlon wagon tailgate hlnge or hatchback Ild and Ilnkage, headl~ght door assembl~es, statlon wagon rear foldrng seat, fuel door hlnge, rear compartment Ihd hlnges
Weatherstr~ps
FLUlDlLUBRlCANT
GM Goodwrench Motor 011 or equivalent for API Se~lce, SFICC or SFICD of the
recommended v~scos~ty
M~xture of water and good qual~ty ethylene glycol base antllreeze conforming to GM spec 1825M (GM Part No 1052753)
Delco Supreme 11
Fluld (GM Part No 1052535) or DOT-3 Fluld
Chass~s grease meetlng requirements of GM-6031M (GM Part No 1052497)
GM power
steerlng flu~d, Part No 1052884 or equivalent
Use lubricant meetlng requirements of GM-4673M (GM Part No 1052182)
DEXR0N'-II Automat~c Transm~ss~on Flu~d (GM Part No 1051855) Camaro and Flreblrd (5 Speed)
Corvette overdr~ve unlt - DEXRON a.II All others SAE-80W-90 GL-5 gear lubr~cant (GM Part No 1052271)
Chass~s grease meetlng requirements of GM-6031M (GM Part No 1052497)
Black Key Lock
Cyl~nders - light oil (GM Par1 No. 1052949)
All other Key Lock Cyl~nders - sllicone lubrlcant (GM Part No 1052277)
Eng~ne 011
Eng~ne 011
Eng~ne 011
Llght 011 (GM Part No 1052949)
Chass~s grease meetlng requirements of GM-6031M (GM Part No 1052497)
SAE
80W or SAE 80W-90 GL-5 (SAE 80W GL-5 In Canada) gear lubricant (GM Part No
1052271)
For Camaro only
- Use SAE BOW190 GL-5+ Hypold 011 (GM Part No 1050010), 11 equ~pped wl5 7L (L98) Englne or 5 OL (LB9) engine wmpeed manual transm~ss~on and disc brakes
All other applications - Use SAE 80W or SAE 80W-90 GL-5 Gear Lubr~cant (GM Part No
1052271)
GM
Opt~kleen Washer Solvent (GM Part No 1051515) or equ~valent
a) Eng~ne 011 b) Chass~s grease meet~ng requirements of GM.6031M (GM Part No 1052497)
Lubricant GM Part No 1051344 grease or equivalent
Eng~ne 011
S~l~cone Grease (GM Part No 1052863) or equivalent

HEATING AND VENTILATION 1A-1
SECTION 1A
NG AND VENT
CONTENTS
General Description ................................. 1A-1
Diagnosis - Heater Trouble ...................... 1A-5
Insufficient Heating or Defrosting .............. 1A-5
Blower Electrical ......................................... 1A-7
....... Improper Air DeliveryINo Mode Shift 1 A-8
Too Much Heat .......................................... 1A-9 ....................................................... Controls 1A-10 ............................................... Blower Noise 1A-11
....................................... On-Vehicle Sewice 1A-13
.......................... Heater Control Assembly 1 A- 13
....................................... Blower Switch 1A- 13
.................................. Temperature Cable
1 A- 13
.......................................... Heater Core 1 A- 13
................................. Vent Control Cable 1 A- 13
Lower Heater Outlet
................................ 1A-14
........................................ Blower Motor 1A-14
GENERAL DESCRIPTION
The base heater system is designed to provide
heating, ventilation, windshield defrosting and on some
cars, side window defogging. Ram air ventilation is
provided on some cars by two (2) outboard vent valves
installed in the plenum. These vent valves are
controlled by push-pull controls mounted in the
instrument panel. When either of these valves are
opened, air will enter the passenger compartment from
the pressurized plenum and be directed to the floor of
the vehicle.
/& VENTILATION
1-FRONT INLET GRILLE
2-BODY LOCK PILLAR EXHAUST VALVE
Fig. 2 Interior Body Air & Exit - Typical Hatchback Models
The power-vent, heat, and defrost provisions of
the base system are controlled within the heater
module. The module itself is composed of two (2)
components
- a blower air inlet and a heater defroster.
The blower air inlet is mounted to the front of the cowl
and the heater defroster assembly is mounted to the
rear of the cowl. A gasket is used between the two to
prevent air, water and noise entrance into the
passenger compartment. Air distribution is through a
heater outlet, defroster duct, power-vent duct work
and outlets.
The three modes of the base heater system (vent,
heat, defrost) are controlled by the functional
assemblies within the heater module. These assemblies
are defined below:
1. Motor & Fan Assembly (Blower).
Provides and regulates air flow from the air inlet
for further processing and/or distribution.
2. Heater Core.
Transfers heat from engine coolant to inlet air,
heating the inlet air.
3. Temperature Valve.
Regulates the amount of air passing through the
heater core, controlling the temperature and mix
of heated and ambient air.
4. Mode (Defroster) Valve.
Regulates the flow and distribution of processed
air to the distribution (heater or defroster) ducts.
5. Vent Valve.
Regulates the flow of non-processed (outside) air
into the passenger compartment.
The operation of these assemblies is controlled by
the levers and switch on the control head. Depending
on model application, two (2) or three
(3) indexed
snap-in cables are attached to the module and control
levers.
The temperature cable has the slider-type,
self-adjust feature. As the temperature lever of the
control head is cycled through its full range of travel,
the cable clip will assume a position assuring that the
temperature valve will seat in both extreme positions.
The vent and/or defrost cables also have the