EATC - Service Tips
Article No.97-8-8
04/14/97
AIR CONDITIONING - EATC SERVICE TIPS
FORD:
1994-97 CROWN VICTORIA, TAURUS, THUNDERBIRD
LINCOLN-MERCURY:
1994-97 CONTINENTAL, COUGAR, GRAND MARQUIS, MARK VIII, SABLE, TOWN CAR
LIGHT TRUCK:
1994-97 EXPLORER
ISSUE:
A number of returned Electronic Automatic Temperature Control (EATC) and Semi Automatic Temperature Control (SATC) system components are found to be not defective. Replacement of these parts may be a result of false codes being stored. This TSB article contains Service Tips pertaining to proper diagnostic procedures.
ACTION:
Refer to the following five (5) Service Tips:
^ 1) Pre-Self Test Procedure
^ 2) Self Test Procedure
^ 3) Diagnostic Trouble Codes (DTCs)
^ 4) Diagnostic Procedure
^ 5) Miscellaneous Diagnostic Tips
SERVICE TIPS
1) Pre-Self Test Procedure
All Automatic Temperature Control Modules
Before starting self test, the vehicle must be stabilized between 4.4 and 32.2°C (40° and 90° F). Keeping the temperature within this range will avoid false Diagnostic Trouble Codes (DTCs) associated with the in-car temperature sensor (031, 030, B1251, B1253) that may occur during extremely cold or hot temperatures.
Make sure the ignition is in the "RUN" position. This will avoid false DTCs associated with the vehicle's communication network. The Automatic Temperature Control (ATC) relies on information received from other modules, and if the ignition is not in the "RUN" position, these modules may not be powered up and communicating with the ATC, thereby causing the ATC to log false communication faults (115, 125, 135, 155, or U1073, U1341, U1234, U1235).
2) Self Test Procedure
1. 1994-97 Town Car, Continental, Mark VIII, Crown Victoria/Grand Marquis, Taurus/Sable, And Explorer:
To enter self test, simultaneously press the "OFF" and "FLOOR" buttons, then release and within 2 seconds press the "AUTO" button. All segments will light up if self test completes with no failures for all above vehicles except Taurus/Sable. For these two vehicles, "888" will be displayed to indicate no failures.
To exit the self test and save all trouble codes, press the blue "COOL" button. To exit the self test and clear all trouble codes, press the "DEF" button.
NOTE:
AFTER WORK HAS BEEN COMPLETED ON THE CLIMATE CONTROL SYSTEM, THE SELF TEST SHOULD BE RE-RUN AND EXITED BY PRESSING THE "DEF" BUTTON. THIS WILL ENSURE THAT ANY CODES ACCIDENTALLY SET DURING REPAIR ARE CLEARED.
2. 1994-97 Thunderbird/Cougar:
The control must be on "AUTO" fan and either "PANEL" or "FLOOR" mode to run on-board diagnostics. To enter the self test, simultaneously press the "COOL" and "OUTSIDE TEMP" buttons, then release and within 2 seconds press the "WARM" button. All segments will light up if the set test completes with no failures.
To exit the self test and save all trouble codes, press the "COOL" button. To exit the self test and clear all trouble codes, press the "OUTSIDE TEMP" button first, and then press the "WARM" button.
NOTE:
AFTER WORK HAS BEEN COMPLETED ON THE CLIMATE CONTROL SYSTEM, THE SELF TEST SHOULD BE RE-RUN AND EXITED BY PRESSING THE "OUTSIDE TEMP" BUTTON FIRST AND THEN THE "WARM" BUTTON. THIS WILL ENSURE THAT ANY CODES ACCIDENTALLY SET DURING REPAIR ARE CLEARED.
3) Diagnostic Trouble Codes (DTCs)
There are two types of DTCs: Hard or Intermittent.
^ Hard DTCs:
Also referred to as "self test," "ON-demand," or "hard" faults. These DTCs are faults that are currently happening within the system at the time of the self test.
^ Intermittent DTCs:
Also referred to as "Run Time," "Continuous," or "Intermittent" faults. These DTCs are faults that have occurred in the past, during assembly processes at the manufacturing plant, during previous vehicle repairs, or normal module operation.
NOTE:
REFER TO THE APPROPRIATE MODEL/YEAR SERVICE MANUAL FOR A LIST OF DTCs AVAILABLE.
4) Diagnostic Procedure
1. Perform self test as described above.
2. Record all DTCs.
3. Exit self test and clear DTCs.
4. Repeat self test as described above.
5. Record any DTCs.
6. Compare DTCs recorded from first and second tests and answer the questions in the table that follows:
5) Miscellaneous Diagnostic Tips
^ On new or low mileage vehicles that have intermittent DTCs stored, exit the self test and clear codes as described in the appropriate self test procedure. These codes were most likely set at the factory during assembly line tests and should be considered FALSE if they do not return during the second self test and are not accompanied by customer symptoms.
^ DTCs 115, 125, 135, and 155 are most likely faults related to the timing of other electronic modules. Under most conditions the ATC control is fully functional.
^ The Powertrain Control/Emissions Diagnosis (PC/ED) Service Manual and New Generation Star (NGS) Tester must be used to diagnose DTCs 115, 125, 135, and 155 that cannot be cleared. These are faults typically associated with a failure in the communication link between the ATC control and other vehicle modules. It is rare that the cause of failure is the ATC control head. Follow the Pinpoint Test in the appropriate model/year Service Manual to diagnose a loss of communication to the ATC control.
^ The following components and functions will never indicate faults through a self test:
NOTE:
THE FUNCTIONS AND COMPONENTS BELOW ARE NOT TESTED DURING A SELF TEST AND MUST BE DIAGNOSED USING THE PINPOINT TESTS.
^ Any blower motor circuit or component failure
^ Any vacuum circuit or component failure
^ Any Cold Engine Lock Out (CELO) circuit or component failure.
^ Some customer concerns may be due to normal operating strategies of the ATC system. Refer to the strategy summary that follows when you think you may have a concern of this type.
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 204000, 204100, 208000, 208100, 208200, 208300, 208999