E46 cabin heat

I have a 2000 328Ci that I've only owned for 6 months, so this may be
a stupid newbie question.

The car developes cabin heat after about 5 minutes of driving on
secondary roads. (~40mph) My commute then switches to a major
interstate for the balance of the trip. (~75mph) After about 30
minutes on the highway the heating system starts blowing cool air.
Not enough to really cool the interior, just enough to make me think
there is a window cracked open. I can increase the temperature
setting (by say 10 degrees) and the cool draft will stop, but the
cabin never reaches the newly set temperature.

My best guess is the water valve as I understand that they are
problematic, but I need input from people who have owned their cars
for much longer to tell if this is a real problem or just the way the
system works.

Is there any reason I can't bypass the water valve as a
troubleshooting step?

thanks,
Mark

On Sun, 16 Jan 2005 14:37:30 -0500, Mark A. Chambers wrote:

> I have a 2000 328Ci that I've only owned for 6 months, so this may be
> a stupid newbie question.
>
> The car developes cabin heat after about 5 minutes of driving on
> secondary roads. (~40mph) My commute then switches to a major
> interstate for the balance of the trip. (~75mph) After about 30
> minutes on the highway the heating system starts blowing cool air.
> Not enough to really cool the interior, just enough to make me think
> there is a window cracked open. I can increase the temperature
> setting (by say 10 degrees) and the cool draft will stop, but the
> cabin never reaches the newly set temperature.
>
> My best guess is the water valve as I understand that they are
> problematic, but I need input from people who have owned their cars
> for much longer to tell if this is a real problem or just the way the
> system works.
>
The valves can fail, but when they do you'll either have no heat at all or
max heat all the time.

It sounds like the system might be working as designed. Once the HVAC
system senses that the cabin has reached the set point it will reduce the
volume of hot water passing through the heater core. This will make the
air coming out of the vents noticeably cooler than it was previously. The
temperature of the air from the vents at that point should be very close
to the set point and cabin temperature.

My 01 525 does this and a check of the air temp coming from the vents
showed it to right at cabin temperature once everything was at steady
state.

All of that presumes that the cabin temperature remains at the set point
during the highway portion of your commute. If the cabin temperature falls
during highway travel I'd be wondering if the engine thermostat might be
faulty. The increased airflow at highway speed could be causing the engine
to run cold if the thermostat wasn't working properly.

--
The instructions said to use Windows 98 or better, so I installed RedHat.

"Jim Levie" > wrote in message
news
> The valves can fail, but when they do you'll either have no heat at all or
> max heat all the time.
>
> It sounds like the system might be working as designed. Once the HVAC
> system senses that the cabin has reached the set point it will reduce the
> volume of hot water passing through the heater core. This will make the
> air coming out of the vents noticeably cooler than it was previously. The
> temperature of the air from the vents at that point should be very close
> to the set point and cabin temperature.
>
> My 01 525 does this and a check of the air temp coming from the vents
> showed it to right at cabin temperature once everything was at steady
> state.
>
> All of that presumes that the cabin temperature remains at the set point
> during the highway portion of your commute. If the cabin temperature falls
> during highway travel I'd be wondering if the engine thermostat might be
> faulty. The increased airflow at highway speed could be causing the engine
> to run cold if the thermostat wasn't working properly.
>

Also, are you certain that the center dash vent control is set to red dots
(heated air), rather than blue (ambient)? On my 328i, air doesn't come
through until after the car is warmed up & I occasionally get cold air in
the auto position when I've neglected to set the dash properly. Ah, the joys
of climate control!

Tom

That's happened to me once before. The way it happened was I had the heat
running full tilt for about 45 minutes to 1 hour (heavy ice day). After that
it just cut out. I think it overheated or something. Went into a mall and
came out about 30 minutes later and all was good. Hasn't done it again, but
since then I've left the heater on the temp control and allowed it to
control itself. Seems to be it best when left to it's own devices...

Deep

"Mark A. Chambers" > wrote in message
...
> I have a 2000 328Ci that I've only owned for 6 months, so this may be
> a stupid newbie question.
>
> The car developes cabin heat after about 5 minutes of driving on
> secondary roads. (~40mph) My commute then switches to a major
> interstate for the balance of the trip. (~75mph) After about 30
> minutes on the highway the heating system starts blowing cool air.
> Not enough to really cool the interior, just enough to make me think
> there is a window cracked open. I can increase the temperature
> setting (by say 10 degrees) and the cool draft will stop, but the
> cabin never reaches the newly set temperature.
>
> My best guess is the water valve as I understand that they are
> problematic, but I need input from people who have owned their cars
> for much longer to tell if this is a real problem or just the way the
> system works.
>
> Is there any reason I can't bypass the water valve as a
> troubleshooting step?
>
> thanks,
> Mark

Yep, on double red. I can't stand the blast furnace effect at triple
red.

Mark

On Sun, 16 Jan 2005 16:59:53 -0500, "Tom Korth"
> wrote:

>
>Also, are you certain that the center dash vent control is set to red dots
>(heated air), rather than blue (ambient)? On my 328i, air doesn't come
>through until after the car is warmed up & I occasionally get cold air in
>the auto position when I've neglected to set the dash properly. Ah, the joys
>of climate control!
>
>Tom
>

Jim,

Thanks for the feedback. I'll try monitoring the cabin versus vent
temperatures.

I had heard from a reputable source that "older" (E36?) BMWs with a
failing water control valve experience heat at low speeds but not at
highway speeds. I wasn't sure if E46s suffered the same issue.

Mark

On Sun, 16 Jan 2005 14:21:12 -0600, Jim Levie >
wrote:

>The valves can fail, but when they do you'll either have no heat at all or
>max heat all the time.
>
>It sounds like the system might be working as designed. Once the HVAC
>system senses that the cabin has reached the set point it will reduce the
>volume of hot water passing through the heater core. This will make the
>air coming out of the vents noticeably cooler than it was previously. The
>temperature of the air from the vents at that point should be very close
>to the set point and cabin temperature.
>
>My 01 525 does this and a check of the air temp coming from the vents
>showed it to right at cabin temperature once everything was at steady
>state.
>
>All of that presumes that the cabin temperature remains at the set point
>during the highway portion of your commute. If the cabin temperature falls
>during highway travel I'd be wondering if the engine thermostat might be
>faulty. The increased airflow at highway speed could be causing the engine
>to run cold if the thermostat wasn't working properly.

I have a '00 323iT, and I have noticed climate control starts feeding in
cool air from console vents when cabin temp reaches target temperature.
However, even when this happens, wind shield and feet seem to get warm air,
which is really neat.

I bet you climate ctrl works as designed.

BR:Z

In article >, Zon says...
>
>I have a '00 323iT, and I have noticed climate control starts feeding in
>cool air from console vents when cabin temp reaches target temperature.
>However, even when this happens, wind shield and feet seem to get warm air,
>which is really neat.

When I'm cooling the interior on a hot day, say 85F outside and inside temp set
to 72, I get warm air on my feet, and cold air above. Which is actually quite
annoying, having hot feet on a hot day. Is there some adjustment I have just
not figured out yet? Something akin to the dial on the dash that adjusts upper
vent temps?

My girlfriend is especially annoyed by this because in hot weather she wears
sandals, so it is more noticeable.


--
Jason G
"This isn't a matter of being tolerant;
it's a matter of being sane." --REP, a.s.c.

"Jason G" > wrote in message
...
> In article >, Zon says...
>>
>>I have a '00 323iT, and I have noticed climate control starts feeding in
>>cool air from console vents when cabin temp reaches target temperature.
>>However, even when this happens, wind shield and feet seem to get warm
>>air,
>>which is really neat.
>
> When I'm cooling the interior on a hot day, say 85F outside and inside
> temp set
> to 72, I get warm air on my feet, and cold air above. Which is actually
> quite
> annoying, having hot feet on a hot day. Is there some adjustment I have
> just
> not figured out yet? Something akin to the dial on the dash that adjusts
> upper
> vent temps?
>
> My girlfriend is especially annoyed by this because in hot weather she
> wears
> sandals, so it is more noticeable.
>
>
Set the centre dash vents to a higher temperature, then reduce the overall
temp at the controller. That will give you the same temp at feet, screen and
face.
Badger.