Auxiliary Heater: When Should It Run?

Hi,

I have a VW T4 Caravelle van with a standing heater. (2.5 TDI)
Accordingly, the timer and other related components are also affected.

This heater is only for the interior of the vehicle and unfortunately does not heat the coolant or the engine itself. However, since cold starts put the most stress on the engine, I would like to find a way to also heat the cooling system.

I also had a pre-installed auxiliary heater.
So far, I haven't been able to determine if this auxiliary heater is actually working. The engine takes quite a long time to warm up. At what temperatures does this type of auxiliary heater activate, and is it possible to modify it in any way?
There must certainly be some kind of monitoring of the outside temperature, and surely there's a way to circumvent it.
Furthermore, how can I even tell if it's running?
The exhaust pipe in the front left wheel well is not getting hot and isn't emitting anything. I've checked this multiple times.
Is it possible to read out this component using VAG-COM? If so, under which menu option?
Furthermore, I've read and heard somewhere that the auxiliary heater can even be converted into a full-fledged engine preheating system.
The most expensive part will probably be the tax clock.
Since I already have that part, I imagine the conversion would be quite simple and inexpensive... (perhaps just splitting the relay contact and running the auxiliary heater at the same time).

Does anyone know how this is assembled, or perhaps have instructions for it?

Hello!

Look over there.
http://www.vw-bus-t4.de/index.php?sid=4, or
http://www.t4-forum.de/t4-forum/faqs/zuheizer.htm

I had a similar upgrade done on my Galaxy (year 2000) which is the same as a Sharan. It cost around €500. It required quite a few hoses, a control unit, and a pump.

Best regards.
Helmut.

Hi,

I found a lot of information on the pages, and after searching through the links provided there, I was also able to find the answers I was looking for.
The auxiliary heater only activates when the engine is running (which was expected), and when the outside temperature is below 5 degrees Celsius.
I also found information on how to bypass the sensor and make it switchable. Thank you very much.

However, I highly doubt that the renovation will cost another 500 euros, as I have already installed almost all of the necessary parts.
I don't need a separate air heater; I already have one with the standing heater. And I also don't need a clock because the standing heater already has one.

So, all that's left is a circulation pump... an electric one. And of course, a few small parts.
I'm sure I can find or order that somewhere.