Air Fan

[Toots]

I have a diesel Avensis Wagon TDi from 2000 and I'm wondering:

If I turn on the air fan to pos. 1 and I leave the airco button off (!!) then the revolution counter (or speed indicator) goes up from about 800 to 1200 rpm.

This only happens when the motor is cold, if it is warm then this effect does not occur.

Is this normal behaviour or is the wiring of the air fan not correct anymore?

[matty2767]

mine does it as well. i suppose the engine is trying to warm the air up but it doesnt have enough heat to generate it so speeds the engine up to compensate.

[Toots]

It is also working when the heating button is set to COLD, so no air has to be warmed up...

...still sounds strange to me!

[Prox]

Its just the extra current drain being put on the alternator, so engine idles up slightly to compensate for the drag. Try switching your lights on and you'll probably find it does the same thing. Perfectly normal,

Regards

Mark

[css]

i agree its normal :)

[lurpak]

If you watched the top gear episode where Jeremy Clarkson drove the lenght of England in a Diesel VW, one of the things he didn;t do was put on the heater fan.This is because it draws current from the Battery and the alternator puts drag on the belt , thus using extra fuel. I have a 1.8 petrol and I really notice the power drain when I stick the Air con on.