1988 PONTIAC FIERO heater

1 A-8 HEATIN,G AND VENVILAVIBN
@ IMPROPER AIR DELIVERY OR NO MODE SHlFT
WITH THE VEHICLE ON AND THE ENGINE WARM, RUN THE FOLLOWING FUNC-
I TIONAL CHECKS. CHECK CABLES FOR EXCESSIVE EFFORT OR BINDING.
POWER VENT
OUTLET HEATER
OUTLET DEFR.
OUTLET
MODE
SIDE
WINDOW
DEFOGGER
OUTLET
VENT NO
AIRFLOW NO
AIRFLOW NO
AIRFLOW AIRFLOW
No I I I
COLD HIGH HIGH VENT AMBIENT
AIRFLOW NO
AIRFLOW NO
AIRFLOW AIRFLOW
No I
HEATER
DEFROSTER COLD HIGH HIGH
TO HOT
COLD
HIGH HIGH
TO HOT NO
AIRFLOW COLD
TO
HOT
AIRFLOW
MINIMUM COLD TO
HOT
AIRFLOW MINIMUM
COLDTO HOT
AIRFLOW
COLD TO
HOT
AIRFLOW MINIMUM
COLD TO HOT
AIRFLOW
MINIMUM COLD TO
AIRFLOW
N 0
AIRFLOW
CONNECTED
& CABLE SHEATH RETAINED
G20025.1A
Fig. 10 Improper Air Delivery Or No Mode Shift Diagnosis

HEATING AND VENTILATION 1A-9
@TOO MUCH HEAT
TEMPERATURE LEVER
TO CONTROL END OF
LOW THE ENGINE
PERATURE DOOR TO WARM UP. WITH
TEMPERATURE HEATER
DEFROST- ER & VENT DOOR
BLOWER INLET & REPAIR
Fig.
11 Too Much Heat Diagnosis.

----
1A-10 HEATING AND VENTILATION
@ CONTROLS
CHECK CABLES FOR ROUTING, KINKEC CABLES,
WIRING INTERFERENCE OR OTHER INSTRUMENT
PANEL INTERFERENCE.
REMOVE CABLE FROM
DOOR(S)
CAUSING BINDING
AND CYCLE
DOOR(§)
MANUALLY. CHECK
FOR DOOR BINDING MOVES
ON
HIGH BLOWER
WlTH A LONGER CABLE AND
ADD A LOOP TO THE CABLE
ROUTING TO INCREASE CONTROL
EFFORT, CHECK INSTRUMENT
PANEL INTERFERENCES
WlTH
NEW CABLE ROUTING TO INSURE
PROPER
OPERATI
INSTALLATION
I
SEAL OK
SHAFT ALIGNMENT, BENT
Fig. 12 Heater Controls Diagnosis

1A-12 HEATING AND VENTILATION
EXAMINE BLOWER FAN FOR WEAR
SPOTS, CRACKED BLADES OR
HUB, LOOSE FAN RETAINING
NUT AND ALIGNMENT. EXAMINE
BLOWER CASE FOR WEAR SPOTS.
REPAIRIREPLACE ASNECESSARY
ANDRECHECK ALL MODES
BUT NOT ALL
TEMPERATURE POSITIONS
AND REMOVE. CHECK MATERIALS AND
HEATERIDEFROSTER REMOVE. CHECK NECESSARY AND
DOOR SEALS. VENT DOOR CHECK SYSTEM
FOR OBSTRUC-
TIONS OR FOREIGN
MATERIALS BE-
TWEEN THE FAN
AND THE TEMPER- ATURE DOOR.
REMOVE, REPAIR
OR REPLACE AS
NECESSARY AND
RECHECK.
Fig.
14 Blower Noise Diagnosis (2 of 2)

HEATING AND VENTILATION 1.4-1 3
ON-VEHICLE SERVICE
HEATER ELECTRICAL WIRING
The heater wiring diagrams are shown in
Electrical Diagnosis, Section
8A, and should be
referred to for diagnosis of electrical problems in the
heater system.
HEATER CONTROL ASSEMBLY AND BLOWER
SWITCH
Remove or Disconnect
1. Negative battery cable.
2.
Control/radio console trim plate.
3. Three
(3) controller retaining screws and pull
controller out from console.
4. Control cables and electrical connections.
5. Blower switch from controller if either switch or
controller requires replacement. If controller is
being replaced, transfer blower switch to new
controller.
Install or Connect
1. When installing controller, install lower right
screw first to properly align controller in console.
2. Blower switch to controller.
3. Control cables and electrical connections.
4. Three (3) controller retaining screws and
controller to console.
5. Control/radio console trim plate.
6. Negative battery cable.
TEMPERATURE CONTROL, POWER VENT,
HEATER DEFROST CABLE
Remove or Disconnect
1. Hush panel(s) (see Section 8C):
a. Temperature
cable - R.H. hush panel.
b.
Heateddefrost cable - R.H. hush panel.
c. Vent
cable
- L.H. hush panel.
2.
Control/radio console trim plate.
3. Three (3) controller retaining screws and pull
controller out from console.
4. Control cable requiring replacement at control
end.
5. Cable at mode control end (temperature cable:
remove cable link cover at crank location).
Install or Connect
1. When installing controller, install right lower
screw first to align control in console.
2. Cable
at mode control end (temperature cable:
install cable link cover at crank location).
3. Control cable at control end.
4. Three (3) controller retaining screws and
contoller in console.
5. Control/radio console trim plate.
6. Hush panel(s) (see Section 8C).
7. Fully cycle controls to adjust cables and check for
proper operation.
HEATER CORE
Remove or Disconnect
Battery ground cable.
Drain cooling system.
Heater inlet and outlet hoses from heater core.
Right lower hush panel (see Section
8C).
ECM attaching screw and move aside.
Right lower I.P. trim panel (see Section
8C).
Lower right I.P. carrier-to-cowl screw.
Four (4) heater case cover screws. Upper left screw
may be reached with a long 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.
Heater case cover.
Core support plate and baffle screws.
Heater core, support plate and baffle from case.
Install or Connect
1. Heater core, support plate and baffle to case.
2. Core support
plate and baffle screws.
3. Heater case cover.
4. Four (4) heater case cover screws.
5. Lower right I.P. carrier-to-cowl screw.
6. Right lower I.P. trim panel (see Section 8C).
7. ECM.
8. Right lower hush panel (see Section
8C).
9. Heater inlet and outlet hoses to heater core.
10. Refill cooling system and check for leaks.
11. Battery ground cable.
VENT CONTROL CABLE (RAM VENT)
Remove or Disconnect 1
1. Hush panel(s) (see Section 8C). R.H. cable
replacement will require removal of both L.H.
and R.H. hush panels.
2. Two
(2) retaining screws and individual vent
control.
3. Unclip
cable control clamp at vent duct and
disengage formed end of cable from door lever.
1 Install or Connect
1. Cable control clamp at vent duct and install
formed end of cable on door lever.
2, Two (2) retaining screws and individual vent
control.
3. Hush
panel@) (see Section 8C).
4. Cycle
control fully and check for proper
operation.
HEATER CONTROL WIRING I
Remove or Disconnect
1. Negative battery cable.

1A-14 HEATING AND VENTILATION
2. Control/radio console trim plate and hush
panels.
3. Three (3) screws holding controller in console
and pull controller out far enough to disconnect
electrical connectors.
4. Blower motor and blower resistor electrical
connections.
5. Carefully pull cowl grommet from cowl and pull
wiring harness through cowl hole into engine
compartment.
Install or Connect
1. When reinstalling controller, install lower right
screw first to align controller.
2. Cowl grommet on cowl and wiring harness.
3. Blower motor and blower resistor electrical
connections.
4. Three (3) screws holding controller in console
and connect electrical connectors.
5. Control/radio console trim plate and hush
panels.
6. Negative battery cable.
HEATER/VENTILATION/DEFROSTER DUCTS
See section 8C for removal.
LOWER (FLOOR) HEATER OUTLET
Remove or Disconnect
1. Console (see Section 8C).
2. L.H. and R.H. hush panels. (see Section 8C).
3. Two (2) floor outlet retaining screws.
4. Floor outlet from core case.
Install 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.
BLOWER MOTOR
Remove or Disconnect
1. Negative battery cable.
2. Electrical connections at blower motor and
blower resistor.
3. Blower motor cooling tube.
4. Blower motor retaining screws and remove
motor/cage assembly from case.
5. Holding blower motor cage, remove cage
retaining screw and slide cage from motor shaft.
Install or Connect
1. Blower motor cage and retaining screw.
2. Blower
motor retaining screws and
motor/cage
assembly in case.
3. Blower motor cooling tube.
4. Electrical connections at blower motor and
blower resistor.
5. Negative battery cable.
6. Reinstall radio capacitor in proper location, if so
equipped.

HEATING AND VENTILATION 1A-17
REMOVAL AND INSTALLATION.
1-CABLE ASSEMBLY - DEFROSTER
4-CONTRO L ASSEMBLY
2-CABLE ASSEMBLY
- VENT 5-BRACKET (HEATER
AND DEFROSTER ASSEMBLY)
3-HEATER AND DEFROSTER ASSEMBLY 6-PUSH NUT
520053-1A
Fig. 603 Heater Controller and Mode Cables

!A-18 HEATING AND VENTILATION
2-CONTROL ASSEMBLY
3-CABLE ASSEMBLY
4-CABLE ADJUSTMENT
Fig. 604 Heater Temperature Control Cable
1. HEATER AND DEFROSTER ASSEMBLY
2. 1.4
N.rn (12 LBS. IN.) INSTALL FIRST
3. CONSOLE ASSEMBLY
4. 1.4 N.rn (12 LBS. IN.)
5. FLOOR OUTLET ASSEMBLY
Fig. 605 Heater Floor Outlet