EATC Blend Door - Intermittenly Goes to Full Heat

Article No.
92-24-7

11/18/92

HEATER - ELECTRONIC TEMPERATURE CONTROL - BLEND DOOR WILL INTERMITTENTLY GO TO FULL HEAT POSITION

FORD:
1988-92 TAURUS

LINCOLN-MERCURY:
1988-92 CONTINENTAL, SABLE

ISSUE:
Electronic Temperature Control blend door may intermittently go to full "heat on" position and remain there until the ignition switch is turned off. The combination of an intermittently open circuit 243 (LG-0) to the blend door coupled with the software routine for the system will lock the blend door in full heat, even if the circuit is closed again the blend door still stays in the full heat position.

ACTION:
Use the following diagnostic procedure to determine if it is necessary to install an actuator and blend door actuator jumper harness.

NOTE:
WHEN THE IGNITION KEY IS CYCLED, THE SYSTEM WILL OPERATE NORMALLY UNTIL IT RECEIVES ANOTHER INTERMITTENT OPEN CIRCUIT SIGNAL, THEN THE PROBLEM OCCURS WHEN THE INTERMITTENT IS OPEN LONG ENOUGH TO DRIVE THE BLEND DOOR PAST A CERTAIN FEEDBACK POSITION.

SERVICE PROCEDURE

When the intermittent "heat on" occurs and can be corrected by turning the ignition switch "off" and then "on", check circuit 243 (LG-0) for an open circuit between the control head and actuator. Refer to the applicable Service Manual, EVTM and the following procedure for service details.

1. Check for cut or damaged wires in circuit 243.

2. Check for broken or loose wires at connectors in the circuit.

3. Check that connectors are properly and solidly connected.

4. Check pin # 15 at Control Head for continuity.

5. Check pin # 4 at Actuator for continuity.

6. If any of the above conditions in steps 1 through 5 are at fault, replace the blend door actuator jumper harness (FODZ-19D887-A).

7. If no fault can be found in step 1 through 5, then replace both the actuator (FODZ-19E616-A) and blend door actuator jumper harness (FODZ-19D887-A).





Part Number/Name Chart

OTHER APPLICABLE ARTICLES:
NONE

WARRANTY STATUS:
Eligible Under Bumper To Bumper Warranty Coverage For 1991 Model Lincolns And All 1992 Models, Basic Warranty Coverage For. All Other Model Years

OPERATION DESCRIPTION TIME
922407A Check EATC System 0.5 Hr.
922407B Check EATC System And 1.2 Hrs.
Replace Blend Door
Actuator Wiring Harness
922407C Check EATC System, 3.6 Hrs.
Replace Blend Door
Actuator And Actuator
Wiring Harness

DEALER CODING
BASIC PART NO. CONDITION CODE
14401 X1

OASIS CODES:
208000, 208300, 208999