heat coming out all the time

[dougyfd]

I have a 1999 mercury sable with electronic ac/ heat control. Heat has started to come out no matter what the temp is set at. From reading various internet sites it seems like the blend door actuator or the door itself is faulty. My questions are 1. Does the radio have to come out to get at either one. 2. Whats the best way to get at each one. Thanks

[shorod]

Yes, the Integrated Control Panel (ICP) has to come out to access the blend door actuator or blend door. The ICP consists of the radio and the electronic automatic temperature control (EATC).

The steps to get to either are somewhat involved, you'll probably want to have a service manual handy if you opt to replace these.

You may want to start by performing the EATC self test to see if it provides any diagnostic codes.

To enter the self-test, press the OFF and FLOOR buttons simultaneously and then press the AUTOMATIC button within two seconds. The display will show a dashed line in the center of the display window. The test may run as long as 30 seconds. Record all DTCs displayed.

e. If any DTCs appear during the self-test, follow the diagnostics procedure given under ACTION for each DTC given.

f. If a condition exists but no DTCs appear during the self-test, refer to the Symptom Chart Condition: EATC System Inoperative, Intermittent or Improper Operation.

g. To exit self-test and retain all intermittent DTCs, push the blue (cooler) button. The control will exit self-test, retain all intermittent DTCs and then turn OFF (display blank).

h. The exit self-test and clear all DTCs, press F-Defrost button. The vacuum fluorescent display window will show 888 and all function symbols for one second. Then, the EATC system will turn OFF (display blank) and all DTCs will be cleared.

Always exit the self-test before powering the system down (system turned OFF). Intermittent DTCs will be deleted after 80 ignition switch ON cycles (after the intermittent condition occurs).

-Rod