EATC stuck on defrost *FIXED*

[SHO_Driver]

It just happened. I pressed on VENT but almost no air would flow through the vents. Every button works meaning the display responds and I hear the regular noises for each button but mostly air flows through the defrost vents and the a/c is always on.

It seems that there may not be enough vacuum to the EATC leaving the unit on Defrost. Anyone fixed this problem before? Or any ideas?

<small>[ September 11, 2003, 02:34 AM: Message edited by: SHO_Driver ]</small>

 

[jelloslug]

Sounds like your blend door actuator is shot. When it goes bad it defaults to defrost. Have fun removing the dash! wink

 

[SHO_Driver]

jelloslug:
Have fun removing the dash! wink

Nooooooooooooooo!
I really hope it won't come to that.

 

[ShoBad236]

Mine does the same thing, i just switch between floor and vent and any others except defrost. It onlys sticks on defrost if i leave it on for awhile. I thought there was something behind the glove box you could change. maybe somebody who knows something can chime in. good luck.

 

[RI-SHO]

Does it still throw air out of the windshield defrost/vent even when the EATC display shows OFF?

If it does I doubt its the blend door acutator, I was told in this thread: http://www.shoforum.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=20;t=001476 it is the BCM about $80 new from Ford or can be found on the forum for sale or even eBay.

 

[SHO_Driver]

RI-SHO:
Does it still throw air out of the windshield defrost/vent even when the EATC display shows OFF?

No, it actually stays off.

 

[Jr's Sho]

If it goes off, then the BCM is good. Run the EATC self-test in hopes something will turn up.

 

[projectSHO89]

I'll repeat - The blend door actuator (BDA) does NOT default to defrost when it fails. It has NOTHING to do with the direction of airflow to any of the the outlet vents. It is there to change the position of the blend door that allows or inhibits airflow through the heater core. Depending on how it fails it will do one of two things - 1) Stay in it's last acutated position (gear/drive failure) or 2) swing to full heat or full "no-heat" (position sensor failure).

Airflow direction to any of the outlet registers is controlled by vacuum motors under the switching control of the the EATC (or manual knobs).

The system is designed to default to DEFROST as a safety measure to insure clear visibility in the event of loss of control of the airflow direction.

First step is to check the vacuum line that routes through the firewall at the heater core connections hole. Try connecting it directly to one of the intake manifold vacuum ports to ensure that it has an adequate vacuum supply. If this does not help, the problem will be due to either some vacuum leak under the dash, a failure of the EATC assembly, or a failed vacuum motor.

If you get under the dash, you will difinitely need the vacuum diagram that is in the service documentation.

Steve

 

[jelloslug]

I have the vacumm diagram if you need it, e-mail me and I will send it to you (I need to scan it first).

 

[RI-SHO]

jelloslug:
I have the vacumm diagram if you need it, e-mail me and I will send it to you (I need to scan it first).

I would defitnaly want it for records or future use, send it to: mailto:[email protected][email protected]</a>.

 

[SHO_Driver]

OK, first thanks for all the replies so far. I ran the self test but it checked out fine with 888. I then dropped the glovebox and looked around. All hoses seem to be intact. There is no vacuum to the defrost vacuum motor. I gave it vacuum (the yellow line) and it moved and switched to vent.

I will try to find the main vacuum hose as Steve was saying to test for vacuum. I'm still trying to locate where on the engine the EATC sources its vacuum. BTW temperature selection works so no blend door problems.

Jelloslug thanks for offering to scan, if I can't figure it out I'll email you.

 

[SHO_Driver]

It works!

After spending enough time following and checking the main vacuum line (black) under the dash, it seemed it was in good shape. I went back under the hood in the middle of the firewall where it exits with the heater core hoses. I traced it as it runs to the passenger side into a T connector.

I unplugged it, ran the car but found there was good vacuum. Just as I was thinking it had to be a bad EATC , the hose broke off in my hand. It had a crack that I couldn't see before. Patched the line and everything works.

Thanks again for everyone's help thumb

 

[Camarok]

jelloslug:
I have the vacumm diagram if you need it, e-mail me and I will send it to you (I need to scan it first).

I am having the exact same problem. It would be awsome if you could email it to me too. [email protected]

Thanks alot! hail