[xQx]

Originally Posted by boonkgang13k

I'm confused if I should turn on A/C during winter. I changed the setting, so that only warm air is coming out. What are the benefits or disadvantages using A/C during winter?

If you need to either cool the air in your car or dry the air in your car you'll want the air conditioner on.

If you want to heat the air in your car, you'll want the heater on.

It is entirely possible to have both the heater and air conditioner on at the same time, giving you warm, dry air in the car.

It's often preferable to run the aircon & heater in winter so your breath doesn't fog up the windows, and so your wet boots can be dried while you're in the car - also drying your carpets and preventing them from going moldy.

If you leave the BMW heater system on full auto and just dial up the temperature you want; you'll find it does all of this for you automatically.

The air conditioner is powered by a pump attached to the engine, so it uses a little bit more fuel and takes a little bit of engine power away from the back wheels compared with when it's turned off. This was/is noticeable in cars with about 40kw of engine power, but you'll never notice the effect of it running all the time in your car. This also means you will have no air conditioning unless the engine is running (idling at least). Air is blown via an electric fan, which uses stuff-all power to operate; and will work even if your engine is turned off.

Originally Posted by boonkgang13k

Also, when the engine is off, the air is not as warm as the engine is on, what should I do?

It is extremely rare for cars to run an electric heating element in their heater. Most cars (It's been very difficult to try to find a schematic of the e82 heating system online) and I'm assuming ours, simply run a second radiator under the dash that's filled with the engine coolant (water). Thus, your heater will only work when your engine coolant is hotter than the cabin. (ie. when the engine is running).

Use your heated seats when you first get in the car. They're heated by an electric element, and thus will provide instant warmth.

[Efthreeoh]

With the Auto climate control system, the A/C does not run at all times when the green light is illuminated. The green light just means the AC compressor is available when needed to condition the air (i.e. for the defrost function).

[RM7]

I had the hardest time with this in my BMW because apart from the temperature select, there's also that temperature select on the vent itself, so when I was trying to get heat and it was cold outside, it would just send ice-cold air at me. Why the hell there's a secondary temperature select on the vent makes no sense to me, but it is what it is. The car wants to run the A/C all the time, most newer cars do, to keep from fogging. When i turn on a car in the winter though, I want heat as soon as possible....

[baege]

Originally Posted by Kooch

I leave it off year round unless I have fogging issues. I can notice the difference between on and off in performance and prefer it off. Personal preference.

I am with ya brotha...just another layer of disconnection I dont need

[Slops]

Mine is always on to prevent fogging up cold windows. That is all

[Z K]

I turn it on if I need to defog my interior windows. Otherwise it is always off.

Driving manual transmission with the AC on takes getting used to. The AC draws power from the car and it changes your clutch engagement points. RPMs drop faster between gears with the AC on and there is noticeable throttle lag.

[Efthreeoh]

Originally Posted by JamesNoBrakes

I had the hardest time with this in my BMW because apart from the temperature select, there's also that temperature select on the vent itself, so when I was trying to get heat and it was cold outside, it would just send ice-cold air at me. Why the hell there's a secondary temperature select on the vent makes no sense to me, but it is what it is. The car wants to run the A/C all the time, most newer cars do, to keep from fogging. When i turn on a car in the winter though, I want heat as soon as possible....

The temp wheel on the center vents is there to mimic older 1980s BMWs with manual HVAC systems. The E21, E24, E28, E30, to name a few, had a HVAC system that allowed cool air to flow from the dash vents, while warm air could flow from the footwell and defroster vents. The temperature dial had to be at or less than 3/4 from highest setting. The purpose was to allow cool air to flow on the driver and front passenger's face and torso in the situation where it was a cold but sunny day, to counteract the solar-warming effect from the sun on the cabin/greenhouse.

[overlook637]

Originally Posted by Radu328i

Time to time you have to turn it on for 5 -10 min. to oil de gaskets and avoid the further leaks.

I read that BMW already does this. Not just for the gaskets but to keep the air ducts from getting musky smelling.

[Jmrdmd]

AC on all year long=no foggy windows

[Fritzer]

Cool and dry is the way to go. The drying factor is my favorite part, even in winter. When I lived in San Diego I would normally leave the air set at it's coolest with AC turned off. Anywhere where it's humid or snows, you will want to have AC most of the time.

[6oclockshadow]

Mine is set to A/C; Auto. Along with the lights, and windscreen wipers. That way my car knows when its raining/snowing and needs defogging/dehumidifying.

[lake_eleven]

Dumb question - how do you set the a/c on Auto - AUTO button next to temp up/down button?

[tranquility]

Originally Posted by lake_eleven

Dumb question - how do you set the a/c on Auto - AUTO button next to temp up/down button?

Ya, if you press AUTO, the A/C is automatically ON iirc.



I know some spammer revived this thread, but anyway, I thought it was always good practice to make sure the A/C is off when switching the car on and moments before one switches it off?

I use AUTO during warmer weather, don't use AUTO/A/C otherwise (unless it automatically switches on when I use the defrost).

[HighlandPete]

Originally Posted by tranquility

Ya, if you press AUTO, the A/C is automatically ON iirc.


I know some spammer revived this thread, but anyway, I thought it was always good practice to make sure the A/C is off when switching the car on and moments before one switches it off?

Got to ask. why? I see no technical (or user) benefit at all to switching on or off, separate to the engine start and stop.

[tranquility]

Originally Posted by HighlandPete

Got to ask. why? I see no technical (or user) benefit at all to switching on or off, separate to the engine start and stop.

I think it's about alleviating stress on the engine when starting and something about clearing out the A/C sys before shutting the car off. I dunno if modern engines now address these issues so there's no need to worry about if the A/C's off or on but I still practice this since it doesn't bother me.

[Germanauto]

I keep A/C on in order to prevent the windows from fogging. Will raise the temp to like 68 though.

[SenorFunkyPants]

Originally Posted by Kooch

I can notice the difference between on and off in performance and prefer it off. Personal preference.

In normal usage...IIRC the A/C compressor and alternator both disconnect when accelerating and reconnect when decelerating?
Low battery and A/C demands notwithstanding.

[M5Rick]

Not good having a/c off for long periods and you have to have it on to prevent windows misting up.

[omasou]

Originally Posted by boonkgang13k

I'm confused if I should turn on A/C during winter. I changed the setting, so that only warm air is coming out. What are the benefits or disadvantages using A/C during winter? Also, when the engine is off, the air is not as warm as the engine is on, what should I do?

Push the auto button, adjust the temp, adjust the fan then forget about it.

Yes, you wan the A/C to run in the winter it will help remove condensation, e.g. windows fogging.

[karolp1993]

Like others, I always keep AC on to prevent windows fogging, in every car.

[RM7]

Originally Posted by tranquility

I think it's about alleviating stress on the engine when starting and something about clearing out the A/C sys before shutting the car off. I dunno if modern engines now address these issues so there's no need to worry about if the A/C's off or on but I still practice this since it doesn't bother me.

There’s no stress on the engine, but if it’s really really cold and you have all kinds of electronics on, your cranking amps need to be sufficient and you might need more than OEM for really cold climates, or you might have to switch off stuff for start. With too many amps required, the engine won’t turn over. Maybe the more modern cars already turn off stuff, but my honda didn’t. Talking about temps well below 0F.