Booster Heater menu on MFD

[Coruscator]

Hi I have a w209 2004 CLK 270 CDI Avantgarde and have a 'Booster Heater' option in my settings menu.
Its controllable by three settings; Automatic, off and A/C off.

I was wondering what specifically this does as I can't find it in my manual.

There is however an 'Automatic Heater' section in the manual which indicates that I should be able to set
on and off times for it but I don't seem to have these time options when I enable the 'Booster Heater'

Please help a confused MB owner.

 

[fingers21]

I think its something to do with getting warm air into the car, before the engine is actually warmed up, because the engines take a fair while to warm properly. I have no time options as far as I know.

 

[whitenemesis]

Booster Heater is an electric kettle type heater bolted to the engine block. It takes excess alternator charge to warm the engine coolant to reduce the time taken to get heat into the cabin. As there generally isn't any excess charge coming from the alternator just after starting the engine it rarely kicks in. I never noticed any benefit on my 270cdi.

The other heater you mention is an optional diesel fuelled burner fitted into the front of side wheel arch. It can be timed to come on prior to starting the engine to preheat the coolant. Its very effective. You would have additional control in the centre console to operate this type of heater. They were very rarely fitted to UK spec vehicles.

 

[Coruscator]

Thanks for your replies guys. That certainly clears things up a bit.

What I don't understand now is why the third setting 'off by A/C off' is
phrased as such.

To my mind, shouldn't it be 'on by A/C off'?

If the booster (when set to activate by A/C off) is used to speed up the
ingress of heat into the cockpit, wouldn't it make more sense to have the
'Booster Heater' come on when the A/C has been switched off?

Maybe I don't understand it correctly.