Has anybody found with these that the climate control takes a while
from when you start the key to actually cooling quickly or heating?

For example, outside temperature 25 degrees climate set at 21 degrees,
you start the engine and get cool air, but only very slowly, it takes
until the car reaches 70 on the temp guage before it goes "Oh right
it's actually quite hot!" and kicks in the air con much more, almost
as if an invisible switch is tripped when the car is up to a certain
temp?

However if I manually overide the system or drop the temp to 14
degrees the desired temp is reached almost instantantly. Similar in
the morning if it's cold I find setting the temp to 30 degrees gets
the car blowing hot air much quicker than if I had just left the
control at 21 degrees.


T_Raymond

T_Raymond gurgled happily, sounding much like
they were saying:

Has anybody found with these that the climate control takes a while from
when you start the key to actually cooling quickly or heating?

Not a 406, but my ol' XM did the same.

For example, outside temperature 25 degrees climate set at 21 degrees,
you start the engine and get cool air, but only very slowly, it takes
until the car reaches 70 on the temp guage before it goes "Oh right it's
actually quite hot!" and kicks in the air con much more, almost as if an
invisible switch is tripped when the car is up to a certain temp?

However if I manually overide the system or drop the temp to 14 degrees
the desired temp is reached almost instantantly. Similar in the morning
if it's cold I find setting the temp to 30 degrees gets the car blowing
hot air much quicker than if I had just left the control at 21 degrees.

Yep. It moderates the fan speed whilst the coolant temp is still low. In
the XM, it took about 1/2 mile, though that was a petrol turbo, so a
chunk less thermally efficient than even an old-tech wheezel.

T_Raymond wrote:
Has anybody found with these that the climate control takes a while
from when you start the key to actually cooling quickly or heating?

For example, outside temperature 25 degrees climate set at 21 degrees,
you start the engine and get cool air, but only very slowly, it takes
until the car reaches 70 on the temp guage before it goes "Oh right
it's actually quite hot!" and kicks in the air con much more, almost
as if an invisible switch is tripped when the car is up to a certain
temp?

However if I manually overide the system or drop the temp to 14
degrees the desired temp is reached almost instantantly. Similar in
the morning if it's cold I find setting the temp to 30 degrees gets
the car blowing hot air much quicker than if I had just left the
control at 21 degrees.

On my Rover 75 it kicks in very rapidly. If the interior of the car is very
hot - then the moment the car is started the climate control automatically
switches to recirculation and the fan comes on full blast. The interior
temperature becomes comfortable in no time at all.

--
Kev

On Wed, 01 Sep 2010 22:38:42 +0100, Ret. boggled us with:

T_Raymond wrote:
Has anybody found with these that the climate control takes a while
from when you start the key to actually cooling quickly or heating?

For example, outside temperature 25 degrees climate set at 21 degrees,
you start the engine and get cool air, but only very slowly, it takes
until the car reaches 70 on the temp guage before it goes "Oh right
it's actually quite hot!" and kicks in the air con much more, almost as
if an invisible switch is tripped when the car is up to a certain temp?

However if I manually overide the system or drop the temp to 14 degrees
the desired temp is reached almost instantantly. Similar in the morning
if it's cold I find setting the temp to 30 degrees gets the car blowing
hot air much quicker than if I had just left the control at 21 degrees.

On my Rover 75 it kicks in very rapidly. If the interior of the car is
very hot - then the moment the car is started the climate control
automatically switches to recirculation and the fan comes on full blast.
The interior temperature becomes comfortable in no time at all.

It takes from one end of the office car park to the other in my 1998
Xantia for the aircon to be blowing cold if I've got the climate control
set on auto. It's about 400yds. Oddly I noticed this today as I had to
wind my window down to swipe out, and I realised it was already blowing
cold so I had to shut the window quickly.



--
Mike P

"T_Raymond" wrote in message
...
Has anybody found with these that the climate control takes a while
from when you start the key to actually cooling quickly or heating?

For example, outside temperature 25 degrees climate set at 21 degrees,
you start the engine and get cool air, but only very slowly, it takes
until the car reaches 70 on the temp guage before it goes "Oh right
it's actually quite hot!" and kicks in the air con much more, almost
as if an invisible switch is tripped when the car is up to a certain
temp?

However if I manually overide the system or drop the temp to 14
degrees the desired temp is reached almost instantantly. Similar in
the morning if it's cold I find setting the temp to 30 degrees gets
the car blowing hot air much quicker than if I had just left the
control at 21 degrees.

It all depends which way the control system has been programmed. Different
climate systems will have different programs and start-up procedures,
obviously the heating (engine temp) and cooling (AC) systems have to get up
to speed before the climate system can be fully functional.
A PID* system tries to keep the temperature constant at whatever you have
set. If it always heated and cooled as fast as it could you would find the
temperature overshooting what you had set and then oscillating between too
hot and too cold for a while. So instead it looks at how much the
temperature has to change and selects a rate of heating or cooling that will
get it there in a reasonable time without too much overshoot.

Check out the graphs on here to see what I mean:
*http://en.wikipedia.org/wiki/PID_controller

Z

It all depends which way the control system has been programmed. Different
climate systems will have different programs and start-up procedures,
obviously the heating (engine temp) and cooling (AC) systems have to get up
to speed before the climate system can be fully functional.
A PID* system tries to keep the temperature constant at whatever you have
set. If it always heated and cooled as fast as it could you would find the
temperature overshooting what you had set and then oscillating between too
hot and too cold for a while. So instead it looks at how much the
temperature has to change and selects a rate of heating or cooling that will
get it there in a reasonable time without too much overshoot.

Check out the graphs on here to see what I mean:
*http://en.wikipedia.org/wiki/PID_controller

Z

After reading a bit more I think I might know what the problem is, or
at least with some guesswork involved.

There are two sensors in the cabin of the 406, one is behind a grill
in the roof next to the interior light, the second is a sunshine
sensor at the front of the top of the dashboard. however there is also
an exterior sensor in the passenger wing mirror which appears to be
malfunctioning, it should be relaying the external temperature to the
display in the car, but all I am getting is a "--" symbol, instead of
a temperature reading.

I'm not sure if it uses this reading in addition to the internal
readings for control of the climate or whether is is just for display
purposes?

T_Raymond

T_Raymond gurgled happily, sounding much like
they were saying:

After reading a bit more I think I might know what the problem is, or at
least with some guesswork involved.

There are two sensors in the cabin of the 406, one is behind a grill in
the roof next to the interior light, the second is a sunshine sensor at
the front of the top of the dashboard. however there is also an exterior
sensor in the passenger wing mirror which appears to be malfunctioning,
it should be relaying the external temperature to the display in the
car, but all I am getting is a "--" symbol, instead of a temperature
reading.

Aha!

I'm not sure if it uses this reading in addition to the internal
readings for control of the climate or whether is is just for display
purposes?

Yes, it does use it for the climate control.

On 01/09/10 17:33, Adrian wrote:

Yep. It moderates the fan speed whilst the coolant temp is still low. In
the XM, it took about 1/2 mile, though that was a petrol turbo, so a
chunk less thermally efficient than even an old-tech wheezel.
My Leon takes a good 3-4 miles to do it in winter.