Heater duct door switching problem

bradhays

Registered
Have an '02 Taurus w/ 103k miles and about 6 months ago all the air, heat or a/c, started blowing only out of the defrost vents at the bottom of the windshield. All the settings work correctly except air has stopped blowing from the floor and dash vents entirely. I know the fix on this is probably easy, just getting to it is gonna be hard. I've had the dash off my '11 Crown Vic to replace the leaking heater core so I've got a little experience doing this sort of thing.

Can any describe to me what switching door in the vent system has gone bad and how I might approach fixing it?

Thanks
 
Most of these cars are designed to kick to defrost as a "fail safe" mechanism. That would give me hope that it's not so much a blend door problem, but a "control" one. Of course '02 is pretty new by my standards.. so I can't be certain that it would still be vacuum controlled by that year.. If yours is Electric, I'd guess I'd be looking at the circuit that controls the blend door motor. Still, checking for vacuum leaks and bad fuses seem like the easiest place to start.

Attempting to run an EATC self-test can't hurt.. The procedure below was copied from here: http://www.idmsvcs.com/2vmod/eatcswap/selftest.html but sure sounds like the Mark VIII procedure I've seen posted elsewhere.

  • 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.
  • 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).


EATC Hard Self-Test FaultsEATC Intermittent Run-Time FaultsNGS DTCDescription
024022B1249Blend door short
025B1249Blend door failure
031N/AB1251A/C in-car temperature sensor open circuit
030N/AB1253A/C in-car temperature sensor short to ground
041043B1255A/C ambient temperature sensor open circuit
040042B1257A/C ambient temperature sensor short to ground
050052B1261A/C solar radiation sensor circuit short to ground
U1041SCP invalid or missing data for function read vehicle speed
U1073SCP invalid or missing data for engine coolant
U1222SCP invalid or missing data for interior lamps
 
Last edited:
Thanks tixer. Found a video on youtube that describes the problem and fix fairly well. Vacuum line like you describe seems to be the most likely cause.
 
I checked all the vac lines on the firewall from the vac source on the driver's side to where it goes into the cabin on the pass side and everything seemed ok. So I get inside and take the glove compartment out and go poking around to see if I can find a loose vac line. Well lo and behold, I did, and lucky enough nothing's broken. I found a loose junction of vac lines that resembles a wiring harness connection. Best guess is it got knocked loose when my aftermarket radio got installed last year. Couldn't find my radio removal tools (on order for next week) so I wasn't able to get as good a view as I wanted, but after a lot of squeezing under the dash to look I never found these lines connection point. Can anyone tell me exactly where these lines plug into?...

WJr55Xl.jpg
 
Driller is correct. That will connect directly to the back of the HVAC control module. My old '86 Town Car used exactly the same connector. There should have been a plastic pin with a "push-on" style metal clip securing that.. if memory serves, it was /very/ difficult to remove, so I'm surprised yours came off so easily. You may want to devise something similar to make sure that doesn't happen again.

I'm glad it was easy to find though! It shouldn't be a difficult fix at all.
 
Back
Top