[btc]

I included a picture to help out some member what we are talking about........

[e30klassic]

That's one of the advantages BMW use electric water pump.

[btc]

Originally Posted by 06graphite

actually, you don't need the key in the slot. that way, if you get out of your car to run into a store for a few minutes, you can leave the heat running to maintain the warmth in the car.

Yes, you are right. I try it without the key and it still work. BTW, that is a great tip to keep your car warm. I'll try that next time when I go to the store.

[ON325i]

How it works is...

once your turn ignition off (after running it for a while, at least the engine have warm air to come out...), you can use the REST button.
You can take your key out, and once you do that, the air current will be much stronger. It will terminate by either...

- You press the REST button again
- You leave it running for 10 minutes

The engine must be off (hence the ignition button pressed) and 'whether the key is pressed in does not make a difference other than the air current since with all the dash board lights turned on, it wll use less power to drive the REST feature. Once you take the key out, the current will be much stronger.