My system only blows cold air, and when I turn system off it goes to defrost automatically.
Any possible answers?
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1998 Lincoln Mark VIII Question: ( EATC ) System
Answer #1mahindra November 23, 2009, 11:28Journeyman
Vehicle Application: 1998 Lincoln Mark VIII LSC 4.6L
Customer Concern: The heater temperature will not switch from hot to cold.
Tests/Procedures: 1. Perform the self test on the Electronic Automatic Temperature Control (EATC) system. To do this, press the OFF and FLOOR buttons at the same time, then release them and immediately press and release the AUTOMATIC button. If it enters the test, the screen will go blank and have a cursor scrolling around. The buttons may need to be pressed several times as the system can be very sensitive to entering the self test.
2. When the test is done, all segments will light, displaying a code 888 if everything is OK. If code 022, 024, or 025 is retrieved, these are codes for the blend door actuator motor. While still viewing the codes, press the DEFROST button. This will cause everything on the display to light up and then the display turns off. This will clear the codes. Recheck operation. In most cases, any codes for a blend door actuator are the fault of the actuator itself.
3. If a pass code is retrieved, but the temperature does not switch from hot to cold when commanded, suspect a broken blend door inside the heater case.
Potential Causes: Broken Temperature Blend Door
Temperature Blend Door Actuator
Tech Tips: When the system detects a blend door actuator fault and stores a code, most of the time the blend door actuator becomes inoperative causing no temperature control until the codes are cleared.