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Alpejohn

Residual heat - hot air for only one minute

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Hi, 

Merry Christmas! 

 

When i turn on the "rest" button (actually called MAX) in my 08/2003 530d,the fan starts and hot air is coming out. But this only lasts for maybe one minute. Then the air gets cold. Utnkeeps blowing air though, for several minutes after. 

 

I do not have the auxiliary water pump under the water valve, and there is no wires to connect it either. I do have a fault code on the aux pump though, thats weird..

Only Electric pump i have is the one on the webasto (wich are working when i turn this rest function on, Ot works fine when running the webasto though

 

Its been reported up to 15 minutes with warm air on rest. But not on my car. 

 

Does anyone has any knowlage on how this system should work? I guess there need to be a pump that cirulates the water to keep it pumping out warm air. 

This is not the case on my car atleast.. <_<

 

Regards 

Fredrik 

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Hi!

I have read about this many places, so i know how it works from a "instruction book" point of view, but im after the more technical point of view.
I guess it has to pump the water to get constant heat, if not it just cools the heatercore..

But i havent found any info on how this actually work, if the car has to have a spesific equipment code or something like that to have the rest function.
Maybe my car doesnt have it, as i dont have the pump at the water valve..  But the function is still there..

I know some has it to get more heat in low speeds etc. but i get very good heat even at idle and i dont have it.


Would like to know how this is actually set up.. But its probably one of those things nobody know, and Bmw them selfe cant even explain it.
So i guess its kind of a lost case.. :-P

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Mine does the same - kind of pointless after a few seconds, as you say - it just cools the heater matrix.

Maybe jump on RealOEM and take a look at the cooling circuit to see if there are any components such as pumps on there.

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2 minutes ago, AlexGSi2000 said:

Mine does the same - kind of pointless after a few seconds, as you say - it just cools the heater matrix.

Maybe jump on RealOEM and take a look at the cooling circuit to see if there are any components such as pumps on there.

 

I guess you dont have the pump at the watervalve either?

RealOEM shows all the types thats avaleble, but both that has webasto but with/without the pump at the water valve says for automatic air cond and webasto.
So there isnt anyhting that tells us why some has the pump, and some dont.. Thats what i really would like to know.. :-P

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Does a diesel engine have the same auxiliary water pump as the gasoline engine?

With gasoline engines I believe it's V8 engines that have the aux pump integrated with the water control valves (below the valves in a single assy), while with L6 engines it's mounted on the lower left of the fan shroud. And I think your diesel engine is an L6, isn't it? Anyway, have a good look. It's visible, barely, from the top but easily visible from below with the lower engine shield removed.

My post in this thread describes methods to check the aux pump.

 

Regards

RDL

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