shaaark89

ok i have a bona fide question here. on my 91 gt after doing some a/c work today i am finding that when the climate conroller has its slider in the recirculation position both fans and the a/c compressor come on regardless of whether the a/c button is depressed or not. if i put it in the center vent position, the a/c and fans come on only if i depress the a/c button (as i would expect and as it works on the '90 and '89.) can anyone verify this as normal or abnormal behavior?

bigs

That is normal behavior.

My '93 does the exact same thing. The reasoning is that when the system is on "recirculate," especially in cold weather, the inside windows will fog up easily. Having the AC come on helps to avoid that.

I was always taught to never use "recirculate" for any extended time in the winter. It'll fog up your windows quickly every time.

Cameron

Yuppers. My '91 GT is the same.

shaaark89

cool (literally)
thanks guys.

mspiegle

I believe the reasoning is because the AC unit is able to remove moisture from the air and thus prevent fogging.

Alan

Yes - this is by 'Intelligent Design' (the real kind) . Max AC and Max heating at the same time - AC to dry the air & heating to evap. clear the windshield - with max Fan and all air to the defrost vents...

I too was sceptical when I read it in the owners manual:

1) That it really operated like this?
and
2) That this was of ANY practical benefit:
A: Would you ever really need to use this? and
B: Would it really work effectively anyway - sounded kind of oddball... ?

Answers:
1) It REALLY does do everything they said...
2) HELL YES!!
A) It is possible for your windshield to fog up fully in about 1 second @ speed so you can't see - ANYTHING (unusual conditions required - but it is possible - guess how I know?)
B) The DEF setting works well in this case about 3-4 seconds (3-4 veeerrryyy looonnngg seconds).

These German engineers were smart - I for one thank them... every single time I think about it...

...

I remember it quite clearly - 80MPH - bright sunny day... near Flagstaff, AZ - SUDDENLY - torrential rain out of bright blue skies...! slowing Wipers - whoa! can't hardly see the road.... ...wipers faster ... fastest - WAIT ...What road! ... WTF ... Hit DEF - arrrgh - Wipes inside windshield with hand - fogs instantly - and too much rain...WTF.... wipes side window looking for any roadside references... ahh where the heck am I?.... drifting slightly to the right - don't what a head-on collision... WAIT- more? - less?... ohhh - hope this is right... where the heck am I? slowing - but not too fast - a truck was right behind me.... mirror - no use! totally fogged ... ahh where the heck am I? - a bit more right maybe.... feel the steering wheel... feel it - what is it saying?... windshield starts to clear just as I feel the rumble strips at the edge of the road - straighten - straighten - good old Arizona rumble strips...thank-you thank-you - whoever you were ... Phew! slowing - look - truck is way behind - slowing - slowing - stops off on shoulder...

Sit silently for several minutes contemplating life - 80 MPH into the abyss - not funny - even now...
the stuff of nightmares...

So - It REALLY does work guys!

- Just remember - if you can't see the road hit DEF fast! - and BTW check that it works occasionally too... you never know...

..... take care near Flagstaff

Alan

morganabowen

Yes, that is consistent with my '91 S-4, but my '82 also did the same thing

AO

Alan - I remember a similar incident when i drove from Flagstaff to Phoenix and it did fog up rather quickly, but that was many years ago.

mackmorrowjr

Glad to hear it. I was getting worried that I had a problem. Wow, what a great forum.