Doug

Hey everyone,

Does switching from Normal AC to MAX AC do anything besides blow harder?
Does the compressor pressure up more or something or what happens exactly??
Not important, but just curious for some time about this.

Regards,

Doug

Stephen

Doug wrote:
> Hey everyone,
>
> Does switching from Normal AC to MAX AC do anything besides blow harder?
> Does the compressor pressure up more or something or what happens exactly??
> Not important, but just curious for some time about this.

I wondered about this myself a few months ago so I looked at my manual.
I wanted to know which setting used the compressor.

Normal AC takes air from outside the cabin and cools it. The air
outside might be very hot so it takes a lot of cooling to bring the
temperature. Max AC cools and recirculates cabin air. That means that
it is further cooling air that it has previously cooled but it also
means you aren't getting much fresh air in the cabin. Use MAX AC when
you first get in and the cab is blasting hot then switch to Norm.

Max AC and Off are the only settings that don't bring in outside air.
This is handy if you get behind a smoking truck, run through a dust
cloud or most importantly travel through an area recently visited by a
skunk or past a mushroom farm. It's not recommended to use MAX AC or
Off for long periods of time because the cabin air can become stale. I
haven't really found this to be true with Max AC but I have for Off.

Off, Panel and Floor are the only settings that do not use the AC
compressor. Panel+Floor does. So if it is cool, you might save a few
farthings on gas by using those settings. Most of the time it's
probably not worth it since AC tends to keep the windows clear.

Stephen

SC Tom

<<snip>> Use MAX AC when
> you first get in and the cab is blasting hot then switch to Norm.

That depends on where you live. Here in SC when it's 95 degrees out with
humidity to match, it's best to start with outside air, then move to max air
after a few minutes. The temp inside my car has been 150 in the full sun,
and trying to cool that rather than the 95 degree outside air is pretty
futile.
Just my $.02, FWIW.

SC Tom

Doug

Alright, thanks guys!! I've actually wondered that for years, and just kept
forgetting about it when in front of this thing until today! It's one of
those things that's not important enough to be hell bent on an answer, but
something just to satisfy curiosity!

Once again, thanks,

Doug


"Stephen" <Steelystephen@coldmail.com> wrote in message
news:kqJOe.194789$9A2.5240@edtnps89...
> Doug wrote:
>> Hey everyone,
>>
>> Does switching from Normal AC to MAX AC do anything besides blow harder?
>> Does the compressor pressure up more or something or what happens
>> exactly?? Not important, but just curious for some time about this.
>
> I wondered about this myself a few months ago so I looked at my manual. I
> wanted to know which setting used the compressor.
>
> Normal AC takes air from outside the cabin and cools it. The air outside
> might be very hot so it takes a lot of cooling to bring the temperature.
> Max AC cools and recirculates cabin air. That means that it is further
> cooling air that it has previously cooled but it also means you aren't
> getting much fresh air in the cabin. Use MAX AC when you first get in and
> the cab is blasting hot then switch to Norm.
>
> Max AC and Off are the only settings that don't bring in outside air. This
> is handy if you get behind a smoking truck, run through a dust cloud or
> most importantly travel through an area recently visited by a skunk or
> past a mushroom farm. It's not recommended to use MAX AC or Off for long
> periods of time because the cabin air can become stale. I haven't really
> found this to be true with Max AC but I have for Off.
>
> Off, Panel and Floor are the only settings that do not use the AC
> compressor. Panel+Floor does. So if it is cool, you might save a few
> farthings on gas by using those settings. Most of the time it's probably
> not worth it since AC tends to keep the windows clear.
>
> Stephen
>

TranSurgeon

some vehicles actually speed up the fan on 'MAX', but on some it just SOUNDS
faster cause the fan noise is ducted back intothe cab on the intake side


"Stephen" <Steelystephen@coldmail.com> wrote in message
news:kqJOe.194789$9A2.5240@edtnps89...
> Doug wrote:
> > Hey everyone,
> >
> > Does switching from Normal AC to MAX AC do anything besides blow harder?
> > Does the compressor pressure up more or something or what happens
exactly??
> > Not important, but just curious for some time about this.
>
> I wondered about this myself a few months ago so I looked at my manual.
> I wanted to know which setting used the compressor.
>
> Normal AC takes air from outside the cabin and cools it. The air
> outside might be very hot so it takes a lot of cooling to bring the
> temperature. Max AC cools and recirculates cabin air. That means that
> it is further cooling air that it has previously cooled but it also
> means you aren't getting much fresh air in the cabin. Use MAX AC when
> you first get in and the cab is blasting hot then switch to Norm.
>
> Max AC and Off are the only settings that don't bring in outside air.
> This is handy if you get behind a smoking truck, run through a dust
> cloud or most importantly travel through an area recently visited by a
> skunk or past a mushroom farm. It's not recommended to use MAX AC or
> Off for long periods of time because the cabin air can become stale. I
> haven't really found this to be true with Max AC but I have for Off.
>
> Off, Panel and Floor are the only settings that do not use the AC
> compressor. Panel+Floor does. So if it is cool, you might save a few
> farthings on gas by using those settings. Most of the time it's
> probably not worth it since AC tends to keep the windows clear.
>
> Stephen
>

Stephen

I think it might have something to do with cab air pressure. I took the
back seat out for trip this month and I discovered something kinda
interesting. Of course there was more road noise without the seats and
seat backs but the cabin vents at the back of the cab were exposed.
They are small rectangular openings with sort of louvres made of
flexible material.

Cab pressure drops when MAX or Off is used, which makes sense because
you are not forcing air into the cab. You can actually see this as the
vents are open with most settings and closed on MAX and OFF. With
nothing to slow the increase/decrease in pressure, you could also feel
your ears pop when switching back and forth.

So...I speculate that maybe when you switch to MAX the fan has less
resistance, that is, that it is not trying to stuff more air into the
cab and increase pressure so it speeds up a little.

Stephen

TranSurgeon wrote:

> some vehicles actually speed up the fan on 'MAX', but on some it just SOUNDS
> faster cause the fan noise is ducted back intothe cab on the intake side
>
>
> "Stephen" <Steelystephen@coldmail.com> wrote in message
> news:kqJOe.194789$9A2.5240@edtnps89...
>
>>Doug wrote:
>>
>>>Hey everyone,
>>>
>>>Does switching from Normal AC to MAX AC do anything besides blow harder?
>>>Does the compressor pressure up more or something or what happens
>
> exactly??
>
>>>Not important, but just curious for some time about this.
>>
>>I wondered about this myself a few months ago so I looked at my manual.
>> I wanted to know which setting used the compressor.
>>
>>Normal AC takes air from outside the cabin and cools it. The air
>>outside might be very hot so it takes a lot of cooling to bring the
>>temperature. Max AC cools and recirculates cabin air. That means that
>>it is further cooling air that it has previously cooled but it also
>>means you aren't getting much fresh air in the cabin. Use MAX AC when
>>you first get in and the cab is blasting hot then switch to Norm.
>>
>>Max AC and Off are the only settings that don't bring in outside air.
>>This is handy if you get behind a smoking truck, run through a dust
>>cloud or most importantly travel through an area recently visited by a
>>skunk or past a mushroom farm. It's not recommended to use MAX AC or
>>Off for long periods of time because the cabin air can become stale. I
>>haven't really found this to be true with Max AC but I have for Off.
>>
>>Off, Panel and Floor are the only settings that do not use the AC
>>compressor. Panel+Floor does. So if it is cool, you might save a few
>>farthings on gas by using those settings. Most of the time it's
>>probably not worth it since AC tends to keep the windows clear.
>>
>>Stephen
>>
>
>
>

JohnR66

"Stephen" <Steelystephen@coldmail.com> wrote in message
news:eVOOe.194889$9A2.10703@edtnps89...
>I think it might have something to do with cab air pressure. I took the
>back seat out for trip this month and I discovered something kinda
>interesting. Of course there was more road noise without the seats and
>seat backs but the cabin vents at the back of the cab were exposed. They
>are small rectangular openings with sort of louvres made of flexible
>material.
>
> Cab pressure drops when MAX or Off is used, which makes sense because you
> are not forcing air into the cab. You can actually see this as the vents
> are open with most settings and closed on MAX and OFF. With nothing to
> slow the increase/decrease in pressure, you could also feel your ears pop
> when switching back and forth.
>
> So...I speculate that maybe when you switch to MAX the fan has less
> resistance, that is, that it is not trying to stuff more air into the cab
> and increase pressure so it speeds up a little.
>
> Stephen

I noticed the pressure on my ears when I switch from MAX to just AC in my
Ranger. I never noticed that in other cars. I'll have to take my altimeter
with me to see how much pressure change there is.
John

dwayne

It blows harder, and closes the damper so it recirculates inside air to be
re-cooled instead of outside air being cooled. Nothing changes as far as the
compressor goes.
"Doug" <DZappyNOSPAM@hotmail.com> wrote in message
news:%4JOe.9622$137.8684@trnddc08...
> Hey everyone,
>
> Does switching from Normal AC to MAX AC do anything besides blow harder?
> Does the compressor pressure up more or something or what happens
> exactly?? Not important, but just curious for some time about this.
>
> Regards,
>
> Doug
>