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SYSTEM WILL NOT TURN ON OR
RUNS INTERMITTENTLY
WORKS WHEN ENGINE IS NOT
RUNNING, SHUTS OFF WHEN
ENGINE IS STARTED.
(TYPICALLY EARLY GEN 4, BUT
POSSIBLE ON ALL VERSIONS)
NOISE INTERFERENCE FROM EITHER IGNITION OR
ALTERNATOR.
INSTALL CAPACITORS ON IGN. COIL, AND ALTERNATOR.
ENSURE GOOD GROUND AT ALL POINTS.RE-LOCATE COIL
AND ASSOCIATED WIRING AWAY FROM ECU AND ECU
WIRING. CHECK FOR BURNED OR LOOSE PLUG WIRES.
IGNITION NOISE (RADIATED OR CONDUCTED) WILL
CAUSE THE SYSTEM TO SHUT DOWN DUE TO
HIGH VOLTAGE SPIKES. IF THIS IS SUSPECTED,
CHECK WITH A QUALITY OSCILISCOPE. SPIKES
GREATER THAN 16V WILL SHUT DOWN ECU.
INSTALL A RADIO CAPACITOR AT THE POSITIVE
POST OF THE IGNITION COIL (SEE RADIO
CAPACITOR INSTALLATION BULLETEN). A FAULTY
ALTERNATOR OR WORN OUT BATTERY CAN ALSO
RESULT IN THIS CONDITION. BATTERY MUST BE
IN GOOD CONDITION FOR ALTERNATOR
REGULATOR TO FUNCTION PROPERLY.
WILL NOT TURN ON UNDER ANY
CONDITIONS
VERIFY CONNECTIONS ON POWER LEAD, IGNITION
LEAD, AND BOTH WHITE GROUND WIRES.
CHECK FOR POSITIVE POWER AT HEATER VALVE GREEN
WIRE. AND BLOWER RED WIRE. CHECK FOR GROUND
ON CONTROL HEAD WHITE WIRE.
VERIFY BATTERY VOLTAGE IS GREATER THAN 10
VOLTS AND LESS THAN 16.
VERIFY PROPER METER FUNCTION BY CHECKING A
KNOWN GOOD BATTERY'S VOLTAGE.
LOSS OF MODE DOOR
FUNCTION
NO MODE CHANGE AT ALL CHECK FOR DAMAGED MODE SWITCH OR POT AND
ASSOCIATED WIRING
PARTIAL FUNCTION OF MODE
DOORS
CHECK FOR OBSTRUCTED OR BINDING MODE
DOORS
TYPICALLY CAUSED BY EVAPORATOR HOUSING
INSTALLED IN A BIND IN THE VEHICLE. BE SURE
ALL MOUNTING LOCATIONS LINE UP AND DON'T
HAVE TO BE FORCED INTO POSITION.
CHECK FOR DAMAGED STEPPER MOTOR OR
WIRING
6. BLOWER TURNS ON AND OFF
RAPIDLY
BATTERY VOLTAGE IS AT LEAST
12V
CHECK FOR AT LEAST 12V BETWEEN GREEN
HEATER VALVE WIRE AND CHASSIS GROUND.
INSURE ALL SYSTEM GROUNDS AND POWER
CONNECTIONS ARE CLEAN AND TIGHT.
BATTERY VOLTAGE IS LESS
THAN 12V
CHECK FOR FAULTY BATTERY OR ALTERNATOR CHARGE BATTERY SYSTEM SHUTS OFF BLOWER AT 10V. POOR
CONNECTIONS OR WEAK BATTERY CAN CAUSE
SHUT DOWN AT UP TO 11V
7. ERATIC FUNCTIONS OF
BLOWER, MODE, TEMP, ETC.
CHECK FOR DAMAGED SWITCH OR POT AND
ASSOCIATED WIRING
REPAIR OR REPLACE
WHEN THE IGNITION IS TURNED
BACKLIGHTING ON CONTROL
BACKLIGHTING ON CONTROL
VINTAGE AIR SUPPLIED PANELS
VINTAGE AIR SUPPLIED PANELS
PANEL ALWAYS ON.
PANEL ALWAYS OFF.
ONLY.
ONLY.
ON, THE BLOWER MOMENTARILY
COMES ON, THEN SHUTS OFF.
THIS IS WITH THE BLOWER
THIS IS AN INDICATOR THAT 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 BATTERY 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 DIRECTLY TO BATTERY.
CONNECT TO GAUGE BACK LIGHT WIRE (0-12V) WHICH
CONNECT TO GAUGE BACK LIGHT WIRE (0-12V) WHICH
TAN WIRE IS ONLY USED ON SYSTEMS WITH
ENTIRE CONTROL PANEL SUPPLIED BY VINTAGE
AIR.
WHICH CONTROLS DIMMING OF PANEL BACK LIGHT
WHICH CONTROLS DIMMING OF PANEL BACK LIGHT
SWITCH IN THE OFF POSITION.
T
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1969-70 MUSTANG w/o AC GEN IV
901271 REV A 2/11/08, 69-70 MUSTANG w/o AC GEN IV EVAP INSTR PG 21 OF 26