BMW heating while engine 'Off'

NYSpeed Automotive
1

(… and after the motor is at operating temp, obviously.)

I know I read somewhere in a manual that you can press the ‘MAX’ button (or some other button) after the vehicle is off and heat will blow into the cabin for up to 15 minutes. But now I can’t find that info anywhere.

:gotme:

I know I didn’t make this up, but I can’t find the exact instructions to know if I’m pressing the right button. Anyone know? I tried twice by pressing the ‘MAX’ button and air blows into the cabin, but it’s not that warm…

2

thats a nice feature if its true

3

The range rover, at least mine, has a mechanical waterpump, so IDK if that would really work…

4

yeah you kind of have to have an electric waterpump to circulate the coolant through the block to the heater core as the heater core cools really fast when no additional hot coolant is circulated through it while the fan is blowing air across it.

maybe it has a pump but its broken?

maybe the system is supposed to use convection or it just doesnt perform as expected.

Brian

5

I know I read it in my manual, and King has it in his manual too. But now I can’t find it. I don’t know how this hocus-pocus magic works, lol.

6

REST button?

7

mine has a “rest” button on the dash in the Heater area… im not sure what it does yet

8

I don’t have a REST button - my climate control is the same as the 6 series I think:

http://blogs.cars.com/photos/uncategorized/landrover_dash2.jpg

9

It does what Josh is talking about. Do a quick a google search. :slight_smile:

10

Ah think I found it:

If you car has a MAX button on the HVAC panel…it will do the same thing. It stands for RESIDUAL…meaning…after the car has warmed up to operating temps…and the ambient temp (outdoors) is 59F or below…you can press the REST button (or MAX) button and warmed air will blow into the cabin when the ignition is turned off.

This is a way to keep the car warmed if you have to stop at a railroad crossing…or make small short trips to the store or bank etc…you can hit the REST or MAX button after turning the ignition off while you run in to take care of your business.

11

http://www.bimmerboard.com/members/q/original/MAX%20AIR%20Instructions.jpg

12

Does it have an auxillary water pump?

13

since the main issue is resolved I have this slightly OT question to ask…

why dont cars come with electric heaters built into the HVAC system to provide heat before the engine is actually warmed up?

14

Love the rest button, and it remembers you heated seat setting too, good stuff.

15

offhand I would say complexity/integration into the regular HVAC system and cost, possibly size since it would have to be somewhat large and most likely would be under the dash

16

Current draw on even a small 3,4kw heater is astronomical on a 120V system, now just imagine it on a 12v system

17

This has nothing to do with an electronic water pump all it is doing is running the hvac blower after the car is off at “full heat” blowing warm air off the heater core into the cabin. My e39 does it as well.

18

Interesting - my e39 has an electronic water pump on the fan shroud along with the mechanical water pump on the block. I didn’t check to see if the electric pump has a seperate circuit to the heater core.

19

there is no way the heater core would provide heat for very long without hot coolant going through it. my accord uses a hot water valve to control interior temp and if you shut the valve off (put it to cold) it instantly loses any heat…

it has to keep circulating hot water somehow.

20

Uh.
take a car without this feature, turn it off, then turn the key to ON… without starting it.
so that the heater fan blows.
it will be warm for about 2 seconds.
then blow ice cold air.
becaaauussee the coolant in the heater core has been chilled?
or i don’t know.
but that’s why i thought it gets cold :stuck_out_tongue:
and it can’t really move…