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CC- A/C - compressor on when A/C lights off - is that normal?

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Hi guys and gals

 

I always start off apologising for asking questions that may be obvious but I’ve done a decent amount of searching and can’t find clarity on this. Just people guessing and not being clear. I am sure the trusty folk here can shed some light on this.

 

I have a 2016 f11 535d. I’ve recently noticed the climate control system using the air con (compressor engaging) even if it’s switched off on the dashboard or if eco pro mode is engaged.

 

I don’t know much about the HVAC system but after trawling the net other model owners with similar generation BMW’s suggest this is all normal and that there is a number of sensors that override the obvious auto/ A/C on/off controls. I’ve also noticed the compressor will disengage after about 5 mins.

In the old days the A/C light on and off meant exactly that.

 

I’m ok with what it is doing but want to know if I have the signs of a fault. 

 

Does anyone know how it is supposed to work?

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I think even with the air con off, if the climate is on "auto" then it'll click the air con on/off as required to keep the front screen clear. There's a sensor of some sort in the housing behind the wing mirror which detects moisture on the screen

 

Or I could just be making that up but I'm sure its BMW that has this 

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13 hours ago, nashdm2 said:

I am not sure I understand what you mean Tarby?

 

Sorry m8. I know its waffle.

 

Air con compressor is engaging without the A/C light and button on. It also comes on when the car is in ecopro mode and also straight from start up. I want to know if this is normal.

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In high end cars with bigger power output engines its common that the A/C compresser runs all the time regardless if the driver wants cool air or not.

 

On 8/1/2018 at 5:26 PM, nashdm2 said:

Can I ask how you know it is engaging please? 

 

Not looked on my F10 but these compressors usually engage drive to their shaft by means of an electrical magnetic clutch in the pulley hub.

 

On my Senator with my engine stopped you could reach in to turn the centre of the hub of the compressor (turning the compressors shaft) without moving the drive belt, the outer part of the pulley was stationary against the belt. When the engine runs the centre of the hub stays still due to the drag/resistance of the compressor. You can see this part not turning and the outer part of the pulley spins round it.

 

Switch on the A/C and you energise the clutch and the centre of the compressor hub now is connected to the part of the pulley in contact with the drive belt.

 

You can usually hear the compressor engage and the engine note changes slightly. Quite obvious if you are looking for it with your head under the bonnet.

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This isn't entirely solved but I am going with what the tech said at BMW when I asked the question at my recent visit (for my brakes). There is real lack of understanding on how this system works on the net. Strange really because its something pretty much all of us have in the cars.

 

What I know it isn't, is the old fashioned style of A/C or Climate control where the A/C part of the cooling is provided by the A/C compressor being engaged by either you pressing the A/C button or a stat or auto switch in the climate control. Also the A/C button being off does not stop the new systems from engaging the A/C compressor.

 

What I was told was that there are all sorts of sensors inside the cabin and in the actual system that will override the manual controls. Once the A/C is engaged (and subsequently the A/C compressor) by one of these automatic means it sometimes can take several minutes to disengage.

 

One way of seeing what is going on is to bring up the image of the car under the efficient dynamics menu and when the illustration of the from vents and the little fan is blue then you know the brain in the climate control is doing something clever is the A/C button light is off. Have a look. It's clever.  I don't know if this is BS, because I cant substantiate it, but the BMW Tech told me that the climate system stores air and recirculates the warm air as hot air!?

 

The only 'for sure' way to know the A/C is off is to switch the system off and open a window! :D

 

You may all wonder why I am nattering on or even bothered by this (having a 535d I am no eco warrior) is because the A/C dries my pesky contact lenses out! Always has and I guess always will.. On all my other cars I could simply ensure the A/C was off. Not now days it seems.

 

 

 

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I’ve had exactly this! I thought I was going mental, albeit my Climate will be a more basic version of yours having a 520d. It’s as you say though, driving along with the auto function on but A/C off, you can feel the air change as soon as it starts kicking our refrigerated air. I’m glad I’m not the only one. 

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Liam - what year is yours? Is it a LCI? 

 

I had one of the very first F10s (a 520 SE) as a company car and i don’t remember it doing this. I also had a e61 for 7 years and it didn’t do it either.

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4 hours ago, -TARBY- said:

Liam - what year is yours? Is it a LCI? 

 

I had one of the very first F10s (a 520 SE) as a company car and i don’t remember it doing this. I also had a e61 for 7 years and it didn’t do it either.

 

Mine’s a 2016 on a 66 plate. Oddly, I had a fair few F10’s as company cars a few years back, all were Pre-LCI from 2011 on a 60 to 13 plates, I also don’t recall any of those doing it. 

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