TROUBLE SHOOTING INFORMATION CONT.
4. SYSTEM WILL NOT TURN ON OR
RUNS INTERMITTENLY
WORKS WHN ENGINE IS NOT
RUNNING, SHUTS OFF WHEN
ENGINE IS STARTED.
(TYPICALLY EARLY GEN 4, BUT
POSSIBLE ON ALL VERSIONS)
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
5. LOSS OF MODE DOOR
FUNCTION
NO MODE CHANGE AT ALL
PARTIAL FUNCTION OF MODE
DOORS
CHECK FOR DAMAGED MODE SWITCH OR POT AND
ASSOCIATED WIRING
TYPICALLY CAUSED BY EVAPORATOR HOUSING
INSTALLED IN A BLIND IN THE VEHICLE. BE SURE
ALL MOUNTING LOCATIONS LINE UP AND DON’T
HAVE TO BE FORCED INTO POSITION.
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.
CHECK FOR FAULTY BATTERY OR ALTERNATOR
INSURE ALL SYSTEM GROUNDS AND POWER
CONNECTION ARE CLEAN AND TIGHT.
CHARGE BATTERY
REPAIR OR REPLACE
CHECK FOR DAMAGED SWITCH OR POT AND
ASSOCIATED WIRING
SYSTEM SHUTS OFF BLOWER AT 10V. POOR
CONNECTIONS OR WEAK BATTERY CAN CAUSE
SHUT DOWN AT UP TO 11V
BATTERY VOLTAGES IS LESS
THAN 12V
7. ERATIC FUNCTIONS OF
BLOWER, MODE , TEMP, ETC.
8. WHEN THE IGNITION IS TURNED
ON, THE BLOWER MOMENTARILY
COMES ON, THEN SHUTS OFF.
THIS IS WITH THE BLOWER
SWITCH IN THE OFF POSITION
THIS IS AN INDICATOR THAT THE SYSTEM HAS
BEEN RESET. BE SURE THE RED POWER WIRE IS 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
RESET.
RUN RED POWER WIRE DIRECTLY TO BATTERY
CHECK FOR OBSTRUCTED OR BINDING MODE
DOORS
CHECK FOR DAMAGED STEPPER MOTOR OR
WIRING
VERIFY PROPER METER FUNCTION BY CHECKING A
KNOWN GOOD BATTERYS VOLTAGE.
VERIFY BATTERY VOLTAGE IS GREATER THAN 10
VOLTS AND LESS THAN 16.
NOISE INTERFERENCE FROM EITHER IGNITION OR
ALTERNATOR
INSTALL CAPACITORS ON IGN. COIL, AND ALTERNATOR.
ENSURE GOOD GROUND AT ALL POINTS. RELOCATE 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 FOR ALTERNATOR
REGULATOR TO FUNCTION PROPERLY.
