Driving the aircon. system?

[barry]

Is it normal for low level warm air to be exiting the face vents when the air con. is selected off?

I would like to be able to access ambient air without any heating component but have not been able to deduce how it can be done.
The car seems to default to low heat for starting when the engine is switched off each time.

Also is there any cooling component available when air is selected to ECON during cruise?

The obvious answer is to run the aircon. permanently in AUTO but it somehow goes against my religion if it isn't neccessary.

Thanks
Barry

[James.uk]

If you open the face vents to outside air it should be at whatever the outside temp is.. You have to turn the horizontal wheel between the middle face vents.. (turn the heater control off.) ...

To get air that is colder than the outside air, then you have to use the air con..

With the heater control working, heat does tend to bleed into the car from under the bonnet..

The central air vent in the rear of the car only delivers air at outside temp, or lower if air con is on. The heat gets to the rear of the car via vents under the seat controlled by the central controls at the front...
...

[SD1too]

Barry,

James' explanation is also in your owner's handbook. It explains the operation of the thumbwheel under the clock.

To answer your question, when 'Econ' is selected the air conditioning is disabled.

I too find that, despite setting the controls to provide cool ambient air only, I get warmish air instead. When the engine is stopped, the fresh air/recirculation intake flap assumes the 'recirculation' position. If the interior of the car is heated by the sun, when the engine is restarted the ATC computer recognises this heat and, in 'Econ' mode, automatically maintains the 'recirculation' setting (as indicated by the LED in the 'recirc.' button). Very hot air is therefore blown out of the vents.

This is one of those annoying things about equipment controlled by a computer. In the majority of cases the cabin temperature is well in excess of the ambient temperature and so fresh air is the right choice to cool down the cabin, not recirculated air. In my view the computer programmers have made a mistake. They would no doubt defend themselves by saying that, in these circumstances, the air conditioning should be used.

The other thing I've noticed about the 75/ZT is the lack of a unimpeded route for fresh air to enter the heater/air conditioner. The pollen filter sits in the plenum chamber which is virtually sealed by various plastic covers. I would imagine that the temperature in here gets quite high when the engine is hot. It seems a rather poor design to me and could also explain the effect you've described.

Simon.

[James.uk]

If, the air con is on auto the air con will only kick in if the temp in the car rises above the selected temp. Otherwise it does nothing..

E.G. auto selected set at 20C outside temp 7c... The car will supply heat.
Temp set at 20c outside temp 20c nothing going on. Temp set at 20c outside air at 25c the air con will cut in and cool the air....

Selecting "Econ" just stops the air con from working..
...

[vitesse-chris]

Originally Posted by James.uk

If, the air con is on auto the air con will only kick in if the temp in the car rises above the selected temp. Otherwise it does nothing..

E.G. auto selected set at 20C outside temp 7c... The car will supply heat.
Temp set at 20c outside temp 20c nothing going on. Temp set at 20c outside air at 25c the air con will cut in and cool the air....

Selecting "Econ" just stops the air con from working..
...

My air con seems to be on all the time on auto

[T-Cut]

Originally Posted by vitesse-chris

My air con seems to be on all the time on auto

Have you tried pressing the Econ button?

TC

[vitesse-chris]

Originally Posted by T-Cut

Have you tried pressing the Econ button?

TC

Yeah, it goes off when I press it, but from the above post, seems it should be automatic?

[SD1too]

Originally Posted by James.uk

If the air con is on auto the air con will only kick in if the temp in the car rises above the selected temp. Otherwise it does nothing..

James,

This is not quite right. In 'auto' the compressor is running constantly to maintain the evaporator at about 4 degrees C. The air conditioning is therefore operating all the time. If the cabin temperature rises above the selected temperature, the air flaps are moved to change the blend of heated air and cooled air until the selected temperature is reached. The system mixes air, it does not turn the compressor on and off.

Temp set at 20c outside temp 20c nothing going on.

Not true. The evaporator will still be cold and the heater matrix will still be hot. The flaps will be set to attempt to maintain 20 degrees C inside the cabin and the blower speed will probably be reduced to very slow. The system is not accurate to one degree, so don't take the selected temperatures too literally.

Temp set at 20c outside air at 25c the air con will cut in and cool the air..

As explained, the air con. is constantly operating when 'auto' is selected. Cool air is always available, so it doesn't "cut in". Turn your thumbwheel under the clock and you'll see.

Originally Posted by vitesse-chris

My air con seems to be on all the time on auto

You're right Chris.

Simon.

Edit: In certain conditions, when the temperature selected is particularly low or high, the compressor will cut out. I have studied this in detail and there appears to be no logical link to ambient temperature and the required interior temperature.

[James.uk]

Ellow SD1.. ..

Soon after having my front fan replaced I was messing under the bonnet with the engine running and the fan was annoying me, So I pressed the "econ" button and the magnetic clutch on the air con dropped out and the front fan stopped running..

I had also had a regass a few days earlier..
...

[SD1too]

Originally Posted by James.uk

... So I pressed the "econ" button and the magnetic clutch on the air con dropped out and the front fan stopped running ...

Ellow James

Yes, that's correct. The 'Econ' mode provides heating and ventilation without air conditioning.

Simon.