HVAC question

[blackonblack]

Just recently noticed that while driving home from work lately that with my Heat and Air control module off is still get hot air from the dash defroster vents and floor vents this stays like this most of the 20 mile ride to and from work on the highway. I tried turning the module on and setting it to vent with cold air and i still get the hot air from the defroster and floor even with the vent blowing cold. Any thoughts, thank you....

[SC Cheesehead]

Chek out these links:

http://www.mercurymarauder.net/forums/showthread.php?t=36922
http://www.mercurymarauder.net/forums/showthread.php?t=59735
http://www.mercurymarauder.net/forums/showthread.php?t=48707
http://www.mercurymarauder.net/forums/showthread.php?t=59516

[4play]

Key on, engine running: Press OFF and FLOOR simultaneously, then press AUTOMATIC within 2 seconds. The EATC will have to run some tests and do some thinking. It may take up to 30 seconds. Soon it may display some codes. Write these down. To exit self test press DEF

EATC System self test error code list

024 Fault in blend door calibration during self test

025 Intermittent fault in blend door calibration

030 Self test indicates automatic temperature control sensor shorted

031 Self test indicates automatic temperature control sensor open

040 Self test indicates ambient sensor short

041 Self test indicates ambient sensor open

042 Ambient sensor intermittent short

043 Ambient sensor intermittent open

050 Self test indicates sunload sensor short

052 Sunload sensor intermittent short

115 Intermittent engine coolant temperature signal

125 Intermittent vehicle speed signal...

a coupple of weeks ago something like that happened to me I got a blend door code, I just cleared the code by pressing the Defrost button after the test was done and it was all better, never had a problem since.

[4play]

Electronic Automatic Temperature Control Module Self-Test


The EATC module self-test will not detect concerns associated with data link messages like engine coolant temperature or vehicle speed signals. A NGS tester must be used to retrieve these concerns.
The EATC module self-test will detect concerns in the system control functions and will display hard diagnostic trouble codes (DTCs) in addition to intermittent diagnostic trouble codes for concerns that occur during system operation. The vehicle interior temperature should be between 4°-32°C (40-90°F) when carrying out the self-test. If the temperatures are not within the specified ranges, false in-car temperature sensor DTCs will be displayed.
The self-test can be initiated at any time. Normal operation of the system stops when the self-test is activated.
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 pulse tracer going around the center of the display window. The test may run as long as 30 seconds. Record all DTCs displayed.
If any DTCs appear during the self-test, follow the diagnostics procedure given under ACTION for each DTC given.
If a condition exists but no DTCs appear during the self-test, refer to the Symptom Chart Condition: The EATC System Is Inoperative, Intermittent or Improper Operation.
To exit self-test and retain all intermittent DTCs, push the blue (cooler) button. The control will exit self-test, retain all intermittent diagnostic trouble codes and then turn OFF (display blank).
To exit the self-test and clear all DTCs, press the DEFROST button. The vacuum fluorescent display window will show 888 and all function symbols for one second. Then, the EATC control assembly 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.

EATC Hard Self-Test Faults
EATC Intermittent Run-Time Faults
NGS DTC
Description
024
022
B1249
Blend door short

025
B1249
Blend door failure
031
N/A
B1251
A/C in-car temperature sensor open circuit
030
N/A
B1253
A/C in-car temperature sensor short to ground
041
043
B1255
A/C ambient temperature sensor open circuit
040
042
B1257
A/C ambient temperature sensor short to ground
050
052
B1261
A/C solar radiation sensor circuit short to ground


U1041
SCP invalid or missing data for function read vehicle speed


U1073
SCP invalid or missing data for engine coolant


U1222
SCP invalid or missing data for interior lamps

[blackonblack]

Thank you for the quick replies, I should have put that I had already run the test on the module and it came up fine. The O-rings sound like it could be the problem, but would it still be the case with the module off..

[cougar9150]

Possibly a vacuum leak on the harness. It is almost sounding like the blend door is not closing. If the AC is on do you still get the traditional groan and clunk of it closing when you shut off the car?

I would also check the line that runs from the air box on the driver side fender well to the T behind the engine just behind the passenger side head. The T then branches off through the firewall and is the input vacuum for the EATC harness. You can get at the harness lying on the passenger side floor looking up under the center console. It may be tied in if it hasn't been pulled out before, don't remember.

It may also be that the door itself is not functioning correctly. If this is the case then the dash needs to come out if I am correct.

[4play]

so your vend doors arent working right? or your hot/ cold is not working right? if with the unit on if all your controls are working right, vent is just vent def is just def etc it's probably not an O ring issue. tho it's such an esy job to replace those I would try it anyway. if not it's probably a blend door issue, or actuator, but if it is were talking around a grand to fix because the whole dash has to come out and it's alot harder then it seems... takes the delership all day to remove one lol.

[FordNut]

99% of the time it's the EATC o-rings.

That's the easiest and cheapest thing to try, so try it first.