23
905069 REV A 4/21/10, 1968 NOVA w/ AC EVAP INSTR PG 23 OF 25
SYSTEM WILL
NOT
TURN ON OR
RUNS INTERMITTENTL
Y
WORKS WHEN ENGINE IS NOT
RUNNING, SHUTS OFF WHEN ENGINE IS ST
AR
TED.
(TYPICALL
Y EARL
Y GEN 4, BUT
POSSIBLE ON
ALL
VERSIONS)
NOISE INTERFERENCE FROM EITHER IGNITION OR AL
TERNA
TOR.
INST
ALL
CAP
ACIT
ORS ON IGN. COIL,
AND
AL
TERNA
TOR.
ENSURE GOOD GROUND
AT
ALL
POINTS.RE-LOCA
TE COIL
AND
ASSOCIA
TED WIRING
AW
AY
FROM ECU
AND ECU
WIRING. CHECK FOR BURNED OR LOOSE PLUG WIRES.
IGNITION NOISE (RADIA
TED OR CONDUCTED) WILL
CAUSE
THE SYSTEM
TO SHUT
DOWN DUE
TO
HIGH VOL
TAGE SPIKES. IF
THIS IS SUSPECTED,
CHECK WITH
A QUALITY
OSCILISCOPE. SPIKES
GREA
TER
THAN 16V WILL
SHUT
DOWN ECU.
INST
ALL
A
RADIO CAP
ACIT
OR
AT
THE POSITIVE
POST
OF
THE IGNITION COIL
(SEE RADIO
CAP
ACIT
OR INST
ALLA
TION BULLETEN).
A F
AUL
TY
AL
TERNA
TOR OR WORN OUT
BA
TTER
Y CAN
ALSO
RESUL
T IN
THIS CONDITION. BA
TTER
Y MUST
BE
IN GOOD CONDITION FOR
AL
TERNA
TOR
REGULA
TOR
TO FUNCTION PROPERL
Y.
WILL
NOT
TURN ON UNDER
ANY
CONDITIONS
VERIFY
CONNECTIONS ON POWER LEAD, IGNITION
LEAD,
AND BOTH WHITE GROUND WIRES.
CHECK FOR POSITIVE POWER
AT
HEA
TER V
AL
VE GREEN
WIRE.
AND BLOWER RED WIRE. CHECK FOR GROUND
ON CONTROL
HEAD WHITE WIRE.
VERIFY
BA
TTER
Y VOL
TAGE IS GREA
TER
THAN 10
VOL
TS
AND LESS
THAN 16.
VERIFY
PROPER METER FUNCTION BY
CHECKING
A
KNOWN GOOD BA
TTER
Y'S VOL
TAGE.
LOSS OF MODE DOOR FUNCTION
NO MODE CHANGE
AT
ALL
CHECK FOR DAMAGED MODE SWITCH OR POT
AND
ASSOCIA
TED WIRING
PAR
TIAL
FUNCTION OF MODE
DOORS
CHECK FOR OBSTRUCTED OR BINDING MODE DOORS
TYPICALL
Y CAUSED BY
EV
APORA
TOR HOUSING
INST
ALLED IN
A BIND IN
THE VEHICLE. BE SURE
ALL
MOUNTING LOCA
TIONS LINE UP
AND DON'T
HA
VE
TO BE FORCED INT
O POSITION.
CHECK FOR DAMAGED STEPPER MOT
OR OR
WIRING
6. BLOWER
TURNS ON
AND OFF
RAPIDL
Y
BA
TTER
Y VOL
TAGE IS
AT
LEAST
12V
CHECK FOR
AT
LEAST
12V BETWEEN GREEN
HEA
TER V
AL
VE WIRE
AND CHASSIS GROUND.
INSURE
ALL
SYSTEM GROUNDS
AND POWER
CONNECTIONS
ARE CLEAN
AND
TIGHT
.
BA
TTER
Y VOL
TAGE IS LESS
THAN 12V
CHECK FOR F
AUL
TY
BA
TTER
Y OR
AL
TERNA
TOR
CHARGE BA
TTER
Y
SYSTEM SHUTS OFF BLOWER
AT
10V
. POOR
CONNECTIONS OR WEAK BA
TTER
Y CAN CAUSE
SHUT
DOWN
AT
UP
T
O 1
1V
7. ERA
TIC FUNCTIONS OF
BLOWER, MODE,
TEMP
, ETC.
CHECK FOR DAMAGED SWITCH OR POT
AND
ASSOCIA
TED WIRING
REP
AIR OR REPLACE
WHEN
THE IGNITION IS
TURNED
BACKLIGHTING ON CONTROL
BACKLIGHTING ON CONTROL
VINT
AGE
AIR SUPPLIED P
ANELS
VINT
AGE
AIR SUPPLIED P
ANELS
PANEL
AL
W
AYS ON.
PANEL
AL
W
AYS OFF
.
ONL
Y.
ONL
Y.
ON,
THE BLOWER MOMENT
ARIL
Y
COMES ON,
THEN SHUTS OFF
.
THIS IS WITH
THE BLOWER
THIS IS
AN INDICA
TOR
THA
T
THE SYSTEM HAS
TAN WIRE IN MAIN HARNESS IS NOT
CONNECTED
TAN WIRE IN MAIN HARNESS NOT
CONNECTED.
BEEN RE-SET
. BE SURE
THE RED POWER WIRE IS
TO 0-12V GAUGE BACK LIGHT
WIRE.
ON
THE BA
TTER
Y POST
AND NOT
ON
A SWITCHED
SOURCE.
ALSO, IF
THE SYSTEM IS PULLED BELOW
7V EVEN FOR
A SPLIT
SECOND,
THE SYSTEM WILL
RE-SET
.
RUN RED POWER WIRE DIRECTL
Y
TO BA
TTER
Y.
CONNECT
T
O GAUGE BACK LIGHT
WIRE (0-12V) WHICH
CONNECT
T
O GAUGE BACK LIGHT
WIRE (0-12V) WHICH
TAN WIRE IS ONL
Y USED ON SYSTEMS WITH
ENTIRE CONTROL
P
ANEL
SUPPLIED BY
VINT
AGE
AIR.
WHICH CONTROLS DIMMING OF P
ANEL
BACK LIGHT
WHICH CONTROLS DIMMING OF P
ANEL
BACK LIGHT
SWITCH IN
THE OFF POSITION.
T
R
O
U
B
L
E
S
H
O
O
T
IN
G
IN
F
O
R
M
A
T
IO
N
C
O
N
T
.
4.
5.
8.
9.
10.