21
901155 REV A 2/22/10, INST 1962-65 NOVA EVAP PG 21 OF 23
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SYMPT
OM
CONDITION
CHECKS
ACTIONS
NOTES
1.
BLOWER ST
AYS ON HIGH
SPEED WHEN IGNITION IS ON
NO OTHER FUNCTIONS WORK
CHECK FOR DAMAGED PINS OR WIRES IN CONTROL
HEAD PLUG.
VERIFY
ALL
PINS
ARE INSER
TED INT
O PLUG. INSURE NO
PINS
ARE BENT
OR DAMAGED IN ECU.
CHECK FOR DAMAGED GROUND WIRE (WHITE) IN CONTROL
HEAD HARNESS.
VERIFY
CONTINUITY
T
O CHASSIS GROUND WITH WHITE
CONTROL
HEAD WIRE
AT
V
ARIOUS POINTS.
LOSS OF GROUND ON
THIS WIRE WILL
RENDER
CONTROL
HEAD INOPERABLE
ALL
OTHER FUNCTIONS WORK
CHECK FOR DAMAGED BLOWER SWITCH OR POT
AND
ASSOCIA
TED WIRING.
SEE BLOWER SWITCH CHECK PROCEDURE (CONT
ACT
VINT
AGE
AIR
TECH SUPPOR
T)
BLOWER ST
AYS ON HIGH
SPEED WHEN IGNITION IS ON OR OFF
.
UN-PLUG 3 WIRE BSC CONTROL
CONNECT
OR
FROM ECU. IF BLOWER SHUTS OFF
, ECU IS EITHER
IMPROPERL
Y WIRED, OR DAMAGED.
BE SURE SMALL, 20GA. WHITE GROUND WIRE IS CONNECTED
TO
THE BA
TTER
Y GROUND POST
. IF IT
IS,
REPLACE ECU.
UN-PLUG 3 WIRE BSC CONTROL
CONNECT
OR
FROM ECU. IF BLOWER ST
AYS RUNNING,
THE BSC
IS EITHER IMPROPERL
Y WIRED, OR DAMAGED.
CHECK
TO INSURE
THA
T NO BSC WIRING IS DAMAGED OR
SHOR
TED
TO VEHICLE GROUND.
THE BSC OPERA
TES
THE BLOWER BY
GROUND SIDE PWM SWITCHING.
THE
POSITIVE WIRE
TO
THE BLOWER WILL
AL
W
AYS BE HOT
.
IF
THE "GROUND" SIDE OF
THE BLOWER IS SHOR
TED
TO
CHASSIS GROUND,
THE BLOWER WILL
RUN ON HI.
REPLACE BSC. (THIS WILL
REQUIRE EV
APORA
TOR
TO BE
REMOVED FROM VEHICLE. )
NO OTHER P
AR
T REPLACEMENTS SHOULD BE
NECESSAR
Y.
2. COMPRESSOR WILL
NOT
TURN
ON (ALL
OTHER FUNCTIONS
WORK)
SYSTEM IS NOT
CHARGED
SYSTEM IS CHARGED
SYSTEM MUST
BE CHARGED FOR COMP
. T
O
ENGAGE.
CHARGE SYSTEM OR BYP
ASS PRESSURE SWITCH .
DANGER- NEVER BYP
ASS SAFETY
SWITCH WITH
ENGINE RUNNING, SERIOUS INJUR
Y CAN RESUL
T
CHECK FOR F
AUL
TY
A/C POT
OR
ASSOC. WIRING
CHECK CONTINUITY
T
O GROUND ON WHITE CONTROL
HEAD WIRE. CHECK FOR 5V ON RED CONTROL
HEAD
WIRE.
TO CHECK FOR PROPER POT
FUNCTION, CHECK
VOL
TAGE
AT
WHITE/BLUE WIRE. VOL
TAGE
SHOULD BE BETWEEN 0
AND 5V
, AND WILL
V
AR
Y
WITH POT
LEVER POSITION.
CHECK FOR DISCONNECTED OR F
AUL
TY
(CHECK FOR F
AUL
TY
PRESSURE SWITCH)
THERMIST
OR.
CHECK
TWO PIN CONNECT
OR
AT
ECU
CHECK CONTINUITY
ACROSS SWITCH
HOUSING.
DISCONNECTED OR F
AUL
TY
THERMIST
OR WILL
REPLACE SWITCH
CAUSE COMPRESSOR
TO BE DISABLED.
3. COMPRESSOR WILL
NOT
TURN
OFF (ALL
OTHER FUNCTIONS
WORK)
CHECK FOR F
AUL
TY
A/C POT
OR
ASSOC. WIRING
REP
AIR/REPLACE POT/CONTROL
WIRING
RED WIRE @
A/C POT
SHOULD HA
VE
APPROX. 5V
WITH IGNITION ON. WHITE WIRE WILL
HA
VE
CONTINUITY
T
O CHASSIS GROUND, WHITE/BLUE
WIRE SHOULD V
AR
Y BETWEEN 0V
AND 5V WHEN
LEVER IS MOVED UP
AND DOWN.
CHECK FOR F
AUL
TY
A/C RELA
Y
REPLACE RELA
Y
FOR '55-56 CHEV
. CHECK FOR PROPER P
ANEL
CONVERSION. CONTROL
LEVERS SHOULD
TRA
VEL
TO WITHIN 1/8" OF BOTH ENDS OF
THE SLOTS.
REFER
TO INTSRUCTIONS "'55-56 CONTROL
P
ANEL
CONVERSION REV B 6 17 05" PDF OR 903055-PCA
REV C
8/10/05 OR LA
TER INSRUCTION MANUAL.
EARL
Y INSTRUCTIONS ON '55-56 CHEV
. DID NOT
INCLUDE P
ANEL
MOD PROCEEDURE FOR
CONTROL
WITH LOWER POT
BRACKET
OFFSET
BACK FROM CASTING. IF LEVERS ONL
Y
TRA
VEL
2/3
TO 3/4 UP
, THIS PROCEEDURE MUST
BE
PERFORMED
REPLACE ECU.
