Download Procedure for Automatic Temp Control (ATC) equipped vehicles

Procedure for Automatic Temp Control (ATC) equipped vehicles:
With the engine ON and the vehicle stopped set the temp to 75*F.
Next hold down the Floor, Mix and Defrost buttons until the ATC
display begins to flash. While the display is flashing, the system will
run it's tests and calibrations.
When the display stops flashing, the tests and calibrations are
complete.
The ATC display can only display one error code at a time. Any stored
codes can be scrolled through by pressing the Panel mode button once
for each code. DO NOT press any other button or you will have to start
the test over. Note the codes and refer to the list below to determine
what system is malfunctioning.
Procedure for Manual Temp Control (MTC) equipped vehicles:
Set the FAN SPEED knob to anything except OFF.
Set the TEMPERATURE knob all the way into the COLD position.
The MODE knob must be in DEFROST.
The A/C button can be on or off.
Press and hold the EBL (electric back light, a.k.a rear windshield
defrost) button until AC00 appears in the odometer display. You will
hear a chime and the A/C light will blink.
Release the EBL button and wait for the A/C light to stop blinking.
Codes will display in the odometer in the form ACxx where xx is the
actual trouble code. Only one code can be displayed at a time, to scroll
through the codes press the A/C button. You will hear a beep every
time the button is pushed. When all codes have been displayed, the
odometer will return to normal. DO NOT push other buttons or turn
any knobs while doing this or the test will be aborted and you will have
to start over.
List of Climate Control DTCs:
23: Blend door actuator feedback failure (bad servo)
24: Mode door actuator feedback failure (bad servo)
25: Ambient temp sensor failure
26: ATC In Car thermister failure (ATC only, bad ATC head or ATC head
disconnected while battery is connected)
27: ATC in car sensor failure (ATC only)
31: Recirculation door actuator stalled (stuck door or bad servo)
32: Blend door actuator stall failure (stuck door or bad servo)
33: Mode door actuator stall failure (stuck door or bad servo)
34: Engine temperature message not received (ATC only, bad ATC
head or bus failure)
35: Evaporator sensor failure
36: ATC control communication failure (bad ATC head or bus failure)
37: Blend door actuator output shorted to battery (bad servo or wiring
fault)
38: Blend door actuator output shorted to ground (bad servo or wiring
fault)
39: Mode door actuator output shorted to battery (bad servo or wiring
fault)
40: Mode door actuator output shorted to ground (bad servo or wiring
fault)
41: Recirculation door actuator output shorted to battery (bad servo or
wiring fault)
42: Recirculation door actuator output shorted to ground (bad servo or
wiring fault)
43: Common door shorted to battery (probable wiring fault, could be a
servo that failed in an odd manner)
44: Common door shorted to ground (probable wiring fault, could be a
servo that failed in an odd manner)
45: A/C control blend door input open or shorted with respect to
ground (MTC only, wiring fault or bad servo)
46: A/C control blend door shorted to battery (MTC only, wiring fault or
bad servo)
47: A/C switch failure (MTC only)
48: A/C control mode door input shorted to ground (MTC only, wiring
fault or bad servo)
49: A/C control mode door input shorted to battery (MTC only, wiring
fault or bad servo)
50: A/C control electric backlite (EBL) switch fails (MTC only)
51: System voltage too low for calibration!!! (check battery cables,
battery and alternator!)