EATC - Blinking Temperature Display
Article No. 85-21-3AIR CONDITIONING - ELECTRONIC AUTOMATIC TEMPERATURE CONTROL (EATC) BLINKING TEMPERATURE DISPLAY
FORD 1985 THUNDERBIRD
LINCOLN-MERCURY 1985 COUGAR, MARK VII, CONTINENTAL
Normally, a blinking temperature display indicates: 1) that the blend door actuator is not in its proper position; or 2) that a short circuit exists in the blend door drive circuit. If, however, there is "electrical noise" or interference of sufficient intensity in the ignition (power) circuit, it could cause a blinking temperature display even though there is no short in that circuit.
Corrective Procedure
To determine the type of corrective action needed, it is necessary to check to see if a short in the circuit actually does exist. The first step in this direction is to duplicate the blinking display by changing the temperature set point. Begin with a temperature setting of 60; proceed to 90; then, back to 60 and up again to 90. Repeat this sequence several times. Allow a 30 second time lapse before changing from one temperature setting to the other. The results should be as follows:
1. If the display does not blink, the difficulty is most likely caused by "electrical noise" or interference in the circuit. To correct this condition, replace the control head.
2. If the display does blink, check the diagnostic codes by depressing "Off" and "Defrost" simultaneously. Then, within 2 seconds, depress "Auto".
^ If the diagnostic code "01" electrical noise" or interference is not the cause of the difficulty.
^ If both "01" and "05" alone are displayed, noise is a probable cause of the blinking temperature display. Replace the control head and repeat the test described previously.
^ If there is no display blink, the condition has been corrected.
^ If the blink still occurs, an actual short circuit exists.
If a self-test error code "01" is displayed alone or replacement of the control head does not correct the condition, proceed with the troubleshooting steps outlined in the Shop Manual, Volume B, Section 36-75-1.
PART NUMBER PART NAME CLASS
E5LY-19980-C EATC Control Assembly C
E5SZ-19980-G EATC Control Assembly C
E5SZ-19980-H EATC Control Assembly C
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: 19980A
TIME: 0.4 Hr. DLR. CODING: Basic Part No. 19980 - Code: 09