Mechanics

CLIMATE CONTROL TEMPERATURE SETTING DISPLAY WILL ONLY INCREASE; CAN RAISE TEMP SETTING, BUT IT WILL NOT GO LOWER. WHY??

2006 Mercury Montego • 95,000 miles

I just purchased a used 2006 Mercury Montego. I have read a lot about "heater blend door" problems and EATC diagnostics, but nowhere have I read the exact symptoms that I am experiencing. When I turned the EATC on the temperature settings for both driver and passenger were set at 75F. Then I can turn on the A/C but the temperature setting buttons to decrease the driver or passenger temperature will not go below 75F. If I raise the temperature the display increases properly, but then it will not go below this newer setting. Right now my settings are 80F-driver and 90F-passenger and they will not decrease. Possible cause: Went to start the car last night and it wouldn't start. The battery cable was extremely loose. Took the cable completely off, cleaned it and replaced/tightened. Car started. But electronic displays for trip counters, etc. Were reset. Noticed that the temperature settings in the EATC were both back to 75F. However, same problem. Can only increase the display settings, never will it go below the setting displayed.
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Montegokps
March 7, 2012.



It sounds like the eatc, but have it scanned for c and u codes. This will remove all doubts.


Merlin2021
Mar 7, 2012.
Does it have steering wheel controls?
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Merlin2021
Mar 7, 2012.
It has steering wheel controls for stereo and cruise control only. I have attached pictures of both controls. I was really curious to know if anyone had heard of the temperature settings controls simply not accepting inputs for lowering the setpoint. The button contacts cannot be bad on both buttons (driver & passenger) at the same time. And pressing either (blue button down) does nothing to the display setting. So I realize I have a problem with my climate control, but was hoping to find out if anyone knew what might be causing the display set points to not lower. Like I mentioned I can raise the temperature setpoints but they will never lower (unless I disconnect power and then they are reset to 75F. But still will not lower).


Tiny
Montegokps
Mar 7, 2012.
You cAN TRY THIS SELF TEST, IF IT WORKS POST ALL CODES SHOWN AND I WILL LOOK IT UP.
Electronic Automatic Temperature Control Module On-Demand Self Test
The EATC Module On-Demand Self Test will retrieve on-demand (hard fault) DTCs only, it will not
retrieve continuous DTCs. Continuous DTCs can be cleared when exiting the EATC Module On-
Demand Self Test. Make sure to retrieve continuous DTCs by carrying out the Electronic Automatic
Temperature Control Module - Retrieve Continuous DTCs procedure before clearing any continuous
DTCs.
 The EATC Module On-Demand Self Test will not detect concerns associated with data link
messages like engine coolant temperature or vehicle speed signals. A scan tool must be used to
retrieve these concerns.
 The EATC Module On-Demand Self Test will detect concerns in the system control functions and
will display on-demand (hard fault) DTCs for concerns that are present during the self-test. The
vehicle interior temperature should be between 4°-38°C (40°-100°F) when carrying out the selftest.
If the temperatures are not within the specified ranges, false DTCs may be displayed.
 The self-test can be initiated after cycling the ignition switch from OFF to ON. Normal operation
of the climate control system stops when the self-test is activated.
 To enter the self-test, press the OFF and DEFROST buttons simultaneously and release, then press
the AUTO button within 2 seconds. The display will show a flashing blower icon for 20 seconds,
after which all vacuum fluorescent segments will be displayed if there are no on-demand DTCs
present. If DTCs are present, the EATC module will display "00 00" and then on-demand DTCs.
Record all DTCs displayed.
 If any DTCs appear during the self-test, carry out the diagnostic procedure. Refer to the
ELECTRONIC AUTOMATIC TEMPERATURE CONTROL MODULE DIAGNOSTIC
TROUBLE CODE INDEX and follow the ACTION for each DTC given.
 If a condition exists, but no DTCs appear during the self-test, GO to SYMPTOM TABLE
Condition: The EATC System Is Inoperative, Intermittent or Incorrect Operation.
 To exit the self-test and retain all DTCs, press any button except DEFROST. The EATC module
will exit the self-test and retain all DTCs.
 To exit the self-test and clear all DTCs, press the DEFROST button. The EATC module will exit
the self-test and all DTCs will be cleared.
 Always exit the self-test before powering the system down (system turned OFF). Once the selftest
is exited, the ignition switch must remain ON for at least 30 seconds to allow the door
actuators to automatically recalibrate.
 Continuous DTCs will be deleted after 80 ignition switch ON cycles after the intermittent fault
occurs.

HVAC CONTROL SYSTEM - GENERAL INFORMATION & DIAGNOSTICS -2006.


Merlin2021
Mar 7, 2012.
Thanks! I will try the self test and report back any DTCs reported.


Tiny
Montegokps
Mar 7, 2012.
I must have some more serious problems than I thought since I cannot get the self test to work. The instructions state to cycle the ignition switch from OFF to ON. It doesn't really state whether to actually start the car or not, but I tried it both ways, then pressed "off" and "defrost" simultaneously, then pressed "auto". Absolutely nothing on the display. So I cannot report any code information. I don't know how the EATC is supposed to work, but when I tried to operate the system normally, if I press the "auto" button, nothing happens. No display (nothing). If I press the "fan" button (bottom left button), then the "auto" button light comes on and the system display states 75 F with the A/C digital display icon. The A/C button light is orange but it will not turn off by pressing the A/C button again. I can only get the A/C button to go out by pressing the "off" button. I guess I'll have to take it in for servicing, but I fear that this will be a costly guessing game for even the dealer. I can only hope it is an easy fix.


Tiny
Montegokps
Mar 8, 2012.
If the self test won't work, have it scanned by someplace that can read the codes properly.


Merlin2021
Mar 8, 2012.

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