A/C - Disproportionate Temp. Change When Knob Adjusted
NUMBER: 24-002-09 REV. AGROUP: Heating & Air Conditioning
DATE: November 12, 2009
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 24-002-09, DATED MAY 6, 2009. ALL REVISIONS ARE HIGHLIGHTED WITH **ASTERISKS** AND INCLUDE A NEW PART NUMBER FOR THE ATC CONTROL HEAD IN CELSIUS.
THE wiTECH DIAGNOSTIC APPLICATION IS THE PREFERRED METHOD FOR FLASHING ECUs.
HELP USING THE wiTECH DIAGNOSTIC APPLICATION FOR FLASHING AN ECU IS AVAILABLE BY SELECTING "HELP" THEN "HELP CONTENTS" AT THE TOP OF THE wiTECH DIAGNOSTIC APPLICATION WINDOW.
THE wiTECH SOFTWARE LEVEL MUST BE AT RELEASE 10.01 OR HIGHER TO PERFORM THIS PROCEDURE.
THE StarSCAN(R) FLASH FILES FOR THIS BULLETIN MUST BE RETRIEVED FROM THE INTERNET.
StarMOBILE DESKTOP CLIENT, STAR MOBILE or StarSCAN MAY ALSO BE USED TO PERFORM THIS PROCEDURE.
SUBJECT:
FLASH - Too Large Of A Temperature Increase When The Temp Knob Is Moved One Or Two Detents from Full Cold Position
OVERVIEW:
This bulletin involves replacing the manual temperature control head on MTC equipped vehicles. **ATC equipped vehicles will require either a flash or ATC control replacement depending on software version. **
MODELS:
2007 - 2008 (WH) Grand Cherokee (International Markets)
2007 - 2008 (WK) Grand Cherokee
2007 - 2008 (W2) Grand Cherokee CKD
2007 - 2008 (XK) Commander
2007 - 2008 (XH) Commander (International Markets)
NOTE:
The MTC portion of this bulletin applies to vehicles built between July 2, 2006 (MDH 0702XX) and January 14, 2008. (MDH 0114XX) equipped with a manual temperature control system (Sales Code HAA).
SYMPTOM/CONDITION:
Customer may complain that panel temperatures increase too rapidly when the temp knob is moved one or two detents from full cold while in manual mode. This service bulletin will provide the customer with smaller, more expected, panel temperature increases per detent move from the full cold temperature knob position.
DIAGNOSIS:
1. Once the vehicle is at operating temperature, place controls to panel mode, adjust temperature to full cold and turn NC on. Turn the blower to High and with the use of a thermometer, measure and record the outlet temperature from the center ducts. This temperature acts as a base point to measure the change in the temperatures between the next few detents. Move the temperature knob one detent towards the hot region (clockwise), wait for the system to stabilize and take another measurement. Repeat this procedure for the next two detentes. Compare the temperature differences between each detent if they are greater then 10 °F (5.5 °C) proceed to Step 2. If the temperature differences are less the 10 °F (5.5 °C) then this bulletin does not apply. The system is operating as it was designed.
2. **Is the vehicle equipped with ATC?
a. Yes > proceed to ATC REPAIR PROCEDURE:
b. No > proceed to MTC REPAIR PROCEDURE:**
PARTS REQUIRED:
MTC REPAIR PROCEDURE:
1. Replace the manual temperature control head. Refer to TechCONNECT for detailed repair procedures, select the SERVICE INFO tab /24 - Heating & Air Conditioning > Controls > Controls A/C Heater Removal and Installation.
2. Perform a manual door calibration:
a. Turn blower motor off
b. Hold the EBL (defrost) button while turning the blower on.
c. Hold EBL for 5 seconds. EBL will blink at 1 HZ until test is complete (approximately 1 minute). Test is complete when the EBL stops blinking.
NOTE:
If EBL and ATC begin to blink then there are diagnostic trouble codes set in the control head requiring further diagnosis.
ATC REPAIR PROCEDURE:
1. Record the ATC control software part number.
2. Does the ATC control p/n end in "55111876ZA"?
a. Yes >> Following procedures in DealerCONNECT > TechCONNECT > Heating and
Air Conditioning > Controls > Control, A/C and Heater > replace the ATC control.
After performing control replacement, initiate the Actuator Calibration function using the scan tool (Refer to Section 28 - DTC-Based Diagnostics/HVAC - Diagnosis and Testing).
b. No >> Control does not require replacement, proceed to Repair Procedure - Flash.
REPAIR PROCEDURE - Flash:
NOTE:
If this flash process is interrupted/aborted, the flash should be restarted.
1. Using the wiTECH Diagnostic Application for flashing an ATC is made available through the wiTECH Diagnostic Application. For instructions select the "HELP" tab on upper portion of the wiTECH window, then "HELP CONTENTS". This will open the Welcome to wiTECH Help screen were help topics can now selected.
2. After reprogramming clear any DTC's that may have been set in other modules due to the reprogramming. The wiTech application will automatically present all DTC's after the flash and allow the tech to clear them.
POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE:
FAILURE CODE:
Disclaimer:
This bulletin is supplied as technical information only and is not an authorization for repair.