A/C MAX Button

[x5south]

Hi Guys, a quick question for you all. I have a 52 plate 3.0i x5. Recently I pressed the A/C MAx button and nothing happened. After work today I jumped in and was playing with the buttons and it seemed to be working fine.

When I returned home I tried it again...... Nothing.

The question i have for you guys does your max button work all the time, I thought they did. After reading on the internet I am getting such a mix response. Some are stating that they only work when the ambient temp outside is above 15 deg.... if that is the case why did mine work earlier today?

If anyone could let me know if their button is working at the moment or can fill me in on what could be wrong I would be very grateful.

Before I look in to this, it would be good to know if this is normal.

Thanks, Stew

[Rusty]

Hi Stew

I understood the button was to recirculate the cabin air through the heater matrix which used the stored heat from the engine to warm it all up again. This would only work if the engine temp was over a certain level and would only work for a short time as was designed to keep you warm whilst you had the engine of at a railroad crossing or the like.

I may be talking out of my ear so feel free to ignore me, but that was my understanding

Cheers

[Turks]

I was pretty sure that the A/C Max button would work all the time... drops the temps to 16 degrees and the fans to full speed? I'm not sure where the thing about the air temp being over 15 degrees has come from... however there maybe some confusion with the following trick:

A/C Max can be used when the engine is switched off and the temperature outside is less than 15 degrees. This will circulate air kept warm by the stored heat in the engine (so obviously after you have driven it). It will stay on for about 30 mins I think. An example is; 20 minute drive to Waitrose, temperature outside is 8 degrees, you park up and switch your engine off then press the MAX button and the fans will start. Go shopping and come out 15 minutes later and step into a car that has been kept warm.


Turks.

[Dan1502]

It works to maximise the aircon cooling when the outside temperature is above 5 degrees and the engine is running and also activates residual heat utilisation when the engine is off and the temperature is below 15 degrees, after having driven and warmed up the engine then stopped. I think the ignition has to be in position 0 for the second function. The idea is to enable windows to be kept clear when stopped for a short period. It's on page 117 of the manual - I checked this as I was wondering why mine wasn't doing anything yesterday but I think it was under 5 degrees at the time.

[x5south]

Thanks for the replies guys. It was 6 degrees here earlier and it seems the 5 degrees theory is correct, thanks for clearing this up for me.
* note to self..."don't try and fix a problem that isn't there" *

[5wany]

Interesting, i'll go and have a play with mines now

AC button that is

[gchristofi]

I've never tried that residual heat options.... mainly because too scared of returning to car and finding a flat battery! Anyone use it regularly without issue?

[Turks]

It would cut out before the battery was too weak to start your car... same as setting the Aux Vent.

I used it quite a lot when I was in my 530d with no problems.


Turks.