A/C and Heater - Cyclical Tapping Noises
NO: 24-15-97 Rev. AGROUP: Heating & A/C
DATE: Dec. 5, 1997
SUBJECT:
HVAC Unit Temperature Door Cyclical Tapping Noise
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 24-15-97 DATED OCTOBER 31, 1997 WHICH SHOULD BE REMOVED FROM YOUR FILES. ALL REVISIONS ARE HIGHLIGHTED WITH **ASTERISKS** AND INCLUDES A VEHICLE PRODUCTION DATE AFTER WHICH THIS PROCEDURE IS NO LONGER NECESSARY.
MODELS:
1998 (LH) Concorde/Intrepid
**NOTE:
THIS BULLETIN APPLIES TO VEHICLES BUILT PRIOR TO NOVEMBER 12, 1997 (MDH-1112XX).**
SYMPTOM/CONDITION:
Some vehicles may exhibit a short cyclical tapping noise as the HVAC unit temperature door cycles against the stop when operating only in full cold position or full hot position. The phenomenon is caused by an erroneous end position data point generated during the initial calibration of the HVAC unit door stops. The condition can also reoccur upon subsequent self-diagnostic/recalibrations of the HVAC system.
NOTE:
ALL VEHICLES SHOULD BE CHECKED FOR THIS CONDITION DURING NEW VEHICLE PREPARATION. IF THE CONDITION EXISTS, PERFORM THE REPAIR PROCEDURE.
DIAGNOSIS:
Verify the condition exists when the temperature door is operating in the full cold or full hot position. Perform the Repair Procedure. For any other noises/conditions refer to the Diagnosis and Testing Section of Group 24 of the 1998 Concorde/Intrepid Service Manual (Publication No. 81-270-8140).
REPAIR PROCEDURE:
This bulletin involves performing the self-diagnostic/recalibration procedure.
1. Place the vehicle in a well-ventilated area and start the engine.
2. Close all windows and doors.
3. For ambient temperatures above 1°C (35°F), set the climate controls to the following settings:
^ Blower knob/speed: high
^ Temperature knob position: full cold or "Lo" (for ATC systems)
^ Mode control position: panel outlets
^ Circulation door position: inside air
^ Air conditioning system: on
For ambient temperatures below 1°C (35°F), set the climate controls to the following settings:
^ Blower knob/speed: high
^ Temperature knob position: full cold or "Lo" (for ATC systems)
^ Mode control position: panel outlets
^ Circulation door position: outside air
^ Air conditioning system: off
4. Allow the vehicle interior to cool for at least 10 minutes.
5. Immediately following step # 4, perform an HVAC system recalibration as follows:
For manual A/C systems:
^ Set the temperature knob to full cold.
^ Set the blower knob to any setting other than Off.
^ Set the mode control knob to Defrost."
^ Press and hold the rear window defrost button for three to five seconds.
^ The A/C LED will begin to flash.
For automatic temperature control systems:
^ Press and hold the MIX," FLOOR," and "DEFROST" buttons for three to five seconds.
^ The ATC display will begin to flash.
6. Allow the system to finish its self-diagnostic/recalibration routine. The self-diagnostic/recalibration routine is complete when display resumes its normal function. If DTC's are generated during the self-diagnostic/recalibration routine refer to page 24-8 of the 1998 Concorde/Intrepid Service Manual.
7. Verify the condition is corrected. If the condition persists repeat the procedure.
POLICY: Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
Labor Operation No: 24-60-20-90 0.2 Hrs.
FAILURE CODE: XX - Service Adjustment