[V.Smurf]

Great analysis ... but I'm not yet convinced that ...

Originally Posted by rwalker

Heat in our cars comes from an engine coolant heat exchanger in the dash.

My experience with both my prior (X5) and current (X6) BMW is that the car heats the cabin well before the engine warms up. And for that to be the case, the most likely source remains the aircon.

Originally Posted by rwalker

A/C in our cars is not a reversible heat pump.

Do you have any factual statement of this? I've tried Dr. Google for some definitive statement, but I'm prepared to admit that I can't get anything one way or the other

Originally Posted by rwalker

It is hugely wasteful to run a pump with engine power when there's a big pile of heat available from running the engine.

No disagreement from me on that: and most likely there is a combination of the engine heat being used once the engine warms up and dry air provided by the aircon. Once this is the case, I'd expect it'd be very difficult to tell the difference in performance in a powerful car like the M2

Originally Posted by rwalker

It is hugely wasteful to run a pump with engine power when there's a big pile of heat available from running the engine.

[url]The lines running from the compressor only go one way: hot/pressure side to the condenser (outside the car), cold/suction side from the evaporator (inside the car).

At my home, where I have aircon installed, there is only a single line between the unit inside my house (which blasts either heat or cold hair depending on the configured temperature). And when it heats the house, the compressor outside is running.

I'm not positive/certain about any of this ... so happy to be corrected.

Cheers!

[rwalker]

Originally Posted by V.Smurf

My experience with both my prior (X5) and current (X6) BMW is that the car heats the cabin well before the engine warms up. And for that to be the case, the most likely source remains the aircon.

Try turning the A/C off if you don't believe me. You don't need to warm the entire engine to run the heater. The taps for the heater core in BMWs come off the head (you know, where the fire is), and coolant in the head gets heat essentially immediately. Newer cars do it better than older cars, but they use the same mechanism.

Originally Posted by V.Smurf

Do you have any factual statement of this? I've tried Dr. Google for some definitive statement, but I'm prepared to admit that I can't get anything one way or the other

Well... my statement is fact . Also, this page will probably be a Google hit for you at some point.

But: if you're looking for someone else to explain how A/C works, I can recommend YouTube.

Originally Posted by V.Smurf

At my home, where I have aircon installed, there is only a single line between the unit inside my house (which blasts either heat or cold hair depending on the configured temperature). And when it heats the house, the compressor outside is running.

Is the line more than an inch in diameter? If so, I think you're looking at the insulation or a conduit wrapped around 2 lines (probably control/electrical in there as well, like at my house). Maybe there's a way to pump refrigerant in a cycle down a single line, but I can't guess what that is.

[geogerf]

Originally Posted by MerlinPurple

+1 ... be thankful it stays on to dry the evaporator.

Nothing worse than the smell of 'moldy' air blowing out the vents. E46M suffered from this issue (no drying) and once the mold is in it's very hard to remove.

Totally agree with you here. In my previous car, I would get into the habit of turning off the A/C and blasting the fan on high 5 minutes prior to parking the car (which all of my passengers hated on hot days). I justified this by not having any mold in the pipes and not getting that sh*t smell.

I've been doing this with the M2 as well. Please tell me if I don't need to!

So to rephrase as a question: if you have the A/C running (light is on) and you park the car, does the system continue to run/blow cold air to dry out the moisture? In my short experience with the car, it does not do this, so I feel I still have to turn off the A/C and blast the fan for a few minutes before locking and walking away from the M2.

I'm eagerly waiting the answer to this!

[geogerf]

Originally Posted by geogerf

Totally agree with you here. In my previous car, I would get into the habit of turning off the A/C and blasting the fan on high 5 minutes prior to parking the car (which all of my passengers hated on hot days). I justified this by not having any mold in the pipes and not getting that sh*t smell.

I've been doing this with the M2 as well. Please tell me if I don't need to!

So to rephrase as a question: if you have the A/C running (light is on) and you park the car, does the system continue to run/blow cold air to dry out the moisture? In my short experience with the car, it does not do this, so I feel I still have to turn off the A/C and blast the fan for a few minutes before locking and walking away from the M2.

I'm eagerly waiting the answer to this!

Anyone have insight on this? Otherwise I'm keeping my weird habit. lol.

[akkando]

Originally Posted by geogerf

Totally agree with you here. In my previous car, I would get into the habit of turning off the A/C and blasting the fan on high 5 minutes prior to parking the car (which all of my passengers hated on hot days). I justified this by not having any mold in the pipes and not getting that sh*t smell.

I've been doing this with the M2 as well. Please tell me if I don't need to!

So to rephrase as a question: if you have the A/C running (light is on) and you park the car, does the system continue to run/blow cold air to dry out the moisture? In my short experience with the car, it does not do this, so I feel I still have to turn off the A/C and blast the fan for a few minutes before locking and walking away from the M2.

I'm eagerly waiting the answer to this!

I think it just turns the air back on without AC when you start the car back up later.

[geogerf]

Originally Posted by akkando

I think it just turns the air back on without AC when you start the car back up later.

Ok that's what it seems like to me.

It would be nice with all the technological advancements that a car could continue to dry the vents after you turn off the engine (of course there should be an option to disable this feature).

[Aronis]

Waited to confirm before posting this.

If you have "Auto" on and manually turn off the A/C (light is off) the A/C WILL COME BACK ON and not show a lit light on the dash. So we really have little control over when the A/C is actually on. Not a real big deal as "auto" does work well, but I think the light should come on when the compressor is active.

Mike

[ZPrime]

Originally Posted by Aronis

Waited to confirm before posting this.

If you have "Auto" on and manually turn off the A/C (light is off) the A/C WILL COME BACK ON and not show a lit light on the dash. So we really have little control over when the A/C is actually on. Not a real big deal as "auto" does work well, but I think the light should come on when the compressor is active.

Mike

Per the manual, in Auto it will re-engage the A/C (even if you've turned it off) if it thinks the interior air is too humid. This is done to prevent window fogging.

[Aronis]

Originally Posted by ZPrime

Per the manual, in Auto it will re-engage the A/C (even if you've turned it off) if it thinks the interior air is too humid. This is done to prevent window fogging.

And I have no problem with that, but the light should come back on to show "a/c" is on.

Mike

[ZPrime]

No disagreement from me, but then it could conceivably drive people crazy wondering why they aren't able to shut off the A/C (or why every time they turn it off it keeps coming back on).

They need a light for "A/C compressor is running" that is separate from "user has enabled A/C". Or a separate indicator light for "A/C automatically came on to dehumidify" or something.

[Bluenose-2er]

Originally Posted by Aronis

Waited to confirm before posting this.

If you have "Auto" on and manually turn off the A/C (light is off) the A/C WILL COME BACK ON and not show a lit light on the dash. So we really have little control over when the A/C is actually on. Not a real big deal as "auto" does work well, but I think the light should come on when the compressor is active.

Mike

I have wondered about this lately. I sometimes turn on Auto to get a quick cool down of the cabin... then turn off the A/C button when I think it is cool enough. But it keeps blowing cool air (cooler than outside) seemingly indefinitely. I have even noticed that out of Auto and with the A/C/ light off my car continues to blow cool air... to the point that there is always a foggy patch where it hits the windshield and condensation is forming on the outside.

Is my car still engaging some Auto (i.e. A/C) functions even with the Auto light off and the A/C light unlit? The condensation patch is really bugging me!

[geogerf]

I never use Auto and I get those symptoms still. I just don’t want that moldy smell to develop over time