EATC Defrost Question/Problem

[cyearns]

I just recently purchased an 02 Mercury Mountaineer and had a question about how the defrost with the EATC should work. When I have it in auto mode with the temp set to about 75 degrees I get plenty hot air out of the floor vents but the air coming out of the defrost vents seems just barley warm or even cold. I can only get hot air out of the defrost vents if I put it to full heat (90 degrees).

Is this the way it is supposed to work or is there a problem there? I was thinking maybe the sun sensor on the dash could be out of wack and telling it to put cool air up there. If that is the problem, how hard/easy is that to replace?

I noticed this problem because normally the temp in the car is just right but my shoulder gets cold from the air coming out the defrost vents.

Any ideas?

Thanks for your help!

 

[Critter92X]

It is normal for the air coming out the top to be cooler than the air coming out at the floor.If it is a big difference though it might not be working right.Mine has the dual EATC and here is what it says in the manual:

(panel/floor) — Distributes air through the instrument panel
registers and the front seat floor ducts. For added customer comfort, the
air distributed through the floor ducts may be slightly warmer than the
air sent to the instrument panel registers.

(floor/defrost) — Distributes outside air through the windshield
defroster ducts, the demister outlets and the front and rear seat floorducts. If the temperature is about 6°C (43°F) or higher, the air
conditioner will automatically dehumidify the air to reduce fogging.
(Note that the A/C indicator does not illuminate when this mode is
selected.) Recirculation and A/C override controls cannot be selected.
For added customer comfort, the air distributed through the floor ducts
may be slightly warmer than the air sent to the windshield defroster
ducts.

I would think if it is an uncomfortable difference then something isn't right.

 

[cyearns]

It doesn't really get uncomfortable unless I have been driving for a while, like an hour or more. I've just been turning up the temp to help compensate for the difference.

It's good to know that in some respects it is fairly normal (I guess I missed that section of the owners manual.)

Any ideas on things I could check to ensure everything is working properly? I have a temp probe I could play with to actually measure the differences in the air temps.

Does anyone know if there is a diagnostic mode for the EATC? On my 96 Cougar it had a self test mode you could do.

 

[Critter92X]

It may be normal the way it is acting.Mine does pretty much the same thing.I leave the temp set on 70* on my side of the truck while my wife sets her side on about 86* because she says it feels like the A/C is blowing out the top vents on her side.I like the way it works myself because on my 92 I leave the window cracked for a little fresh air while the heat is going and on the 02 I don't need to,it blows just enough cool air from the vents to keep me happy.

 

[Critter92X]

BTW,welcome to the site.You will find most anything you need by looking around on here.I'm sure someone that knows more about the 3rd generations can tell you if yours is acting normal.I've only had my 02 for about 6 weeks so I don't know much about them yet.I'm still learning stuff about my 1st generation Ex.lol!

 

[cyearns]

Thanks for the welcome! I used to be active in a Cougar/Thunderbird forum, but I haven't owned Mercury for a couple years now, it's good to be back in one, even though I haven't owned it a week yet.

Anyone around know about the EATC self test? I know the older generations had one and I haven't been finding anything using the search.

 

[Critter92X]

I haven't tried this but I found it on the net.Hope it might help.

EATC Diagnostics

 

[cyearns]

Thanks! I found a similar page (already had the Press Off & Floor then Automatic written a post-it note!), just hope it applies to the EATC unit that is in my Mountaineer. I'll let you guys know if it works.

 

[cyearns]

Well it doesn't look that process works for the 2002 model. Has anybody found or know of another way to start the diagnostics on the EATC?