Join Date: Nov 2011
Location: Waterloo, ON, Canada
Search the forum there is a procedure to reset the ATC head when ever its disconnected (not self diag) Try this...
This is what the FSM says in case you don't have one
RECALIBRATING YOUR AC:
1. Start the engine but do not move the vehicle.
2. Set the Temp control to 75 degrees.
3. Press and hold the Floor, Mix (vent/defrost) and Defrost buttons at the same time. The floor is a bottom button and the others are upper.
4. The control head will begin to blink and enter a diagnostic mode.
5. Release the Floor, Mix and Defrost buttons.
Once the unit has gone through its diagnostics it will either return to its normal mode (with all air doors calibrated) or it will return one or more of 16 different error codes between 23 and 51. The ATC control can only show one diagnostic trouble code at a time. Under certain circumstances, more than one diagnostic trouble code could be in the membory. To scroll through any additional diagnostic trouble codes, press the Panel Mode button on the ATC control. Any other button or turning of a knob will end the diagnostic test without showing the rest of the trouble codes.
TESTING YOUR AC SYSTEM:
1) Manually set the blower fan to HIGH - fully clockwise.
2) Set the temperature to "Lo"
3) Push the "recirc"button to engage the recirculate mode.
4) Hold the engine speed to 1,000 RPM. The engine should be warmed up, and close all doors and windows.
Insert a thermometer in the left center dash vent (all dealers have these; you can get one at an auto parts store if you don't have one. It looks like a meat thermometer, with a long probe in the rear). With an outside ambient temperature of 70 degrees F, the A/C outlet temp should be no more than 42 degrees F. At 80 degrees, no more than 45. At 90, no more than 50, and 100 degrees, no more than 54. These numbers will drop slightly if you were to drive the car due to the increased airflow across the condenser. If the temperature exceeds these values, then it is not performing properly and requires service.
STANDARD PROCEDURE - HVAC SYSTEM CALIBRATION:
This procedure may be performed on both the ATC and MTC systems.
1. Start engine and let run.
2. If the vehicle has an ATC system, turn the control head on.
3. Set the temperature controls to the full cold position for two minutes.
4. Set the temperature controls to the full heat position for five minutes.
Reset to desired temp. and put back in auto mode -- air should be much colder.
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