Webasto diesel heater control question.

g4jsg

Member
My van has a webasto diesel heater with one vent and a rotary dial with green led in the middle when it’s on.

My question is how do you control the heat & fan speed separately? Last night was our first overnight trip, in the lakes and it was wet & cold, and the heater just seemed to be on full fan all the time, the rotary dial didn’t make it get hotter or cooler, nor did it change the fan speed. So how do you get low heat & quiet fan speed to keep the van warm overnight?

Thanks
John
 

andys

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Haven't you got a thermostat knob? Usually you would just set it to the temperature you want and it will do a 747 impression until it gets to that and then will automatically slow down until it just needs to be on very quietly to maintain temperature.
 

g4jsg

Member
The rotary dial is supposed to set a temp and I was told it would get to temp then shut if the fan or the fan goes to low speed at least, but last night it was just baking hot and high fan speed no matter how far around the dial was set. So I’m wondering where the internal temp sensor is?
 

andys

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Yeah that doesn't sound right, mine starts slowing down after about 10 mins, though I don't like it too warm.
 

g4jsg

Member
I’ve seen different controls for webasto with dual temp & fan speed controls, so does anyone know if you can change the heater control easily?
 

scotia

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@g4jsg did you get this sorted? @andys - what controller do you have?

i was going to add an external temps sensor but im not sure it'll do anything more? The temp sensor for the Hd controller is just by the rotary knob and the external one has a cable 5m long so i could put it further back in the van to get a better temp..
 

andys

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@g4jsg did you get this sorted? @andys - what controller do you have?

i was going to add an external temps sensor but im not sure it'll do anything more? The temp sensor for the Hd controller is just by the rotary knob and the external one has a cable 5m long so i could put it further back in the van to get a better temp..
It’s not a separate controller, it’s the standard Westfalia control panel that controls fridge, heating and timer and displays temperature and water tank levels
 

scotia

Senior Member
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ah ok.. damn. trying to understand why mine doesnt seem to turn off like it should under a thermostat.. i thought it should..?! it just goes for 15 or 20 or how ever long we program it for.. i need to look into this!
 

oldiebut goodie

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The rotary dial is a rheostat not a thermostat. The temperature of the air entering the heater is measured by the ecu and compared with the setting of the rheostat and the heat output adjusted accordingly. Of course if you are running an Air Top 2000 that is just on its limit of capability if you have a poptop open leading to high heat loss. VW fitted an Air Top 3500ST as the factory fit heater on T5s. Running a 2000 is fine most of the time as it is better for the heater to run full out most of the time avoiding early coking up. The fan and heat will only diminish when the heat has reached the set point.
You can add an external air temp sensor easily enough which can then be sited so that it is regulating according to the temp at that height rather than floor level where it is always a lot colder than the body feels halfway up the van.
(Although when my van arrives ( a lwb high top ) I shall be fitting an Air Top Evo 40 which is 4Kw using the VW underslung mount, but then I repair Webasto heaters so it doesn't worry me)

The approximate temperatures for the rheostat are shown below. ( When I sell a heater I usually put a small felt pen mark at 20°C by looking at the setting with the computer)

rheostattemps.jpg
 

oldiebut goodie

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Cross posted from your new thread - will keep any further posts there to avoid confusing this original post.

The multifunction controller works just the same - the dial adjusts the setpoint temp and the air temp is measured at the heater still. A thermostat as such is not used normally ( I have seen a suitable thermostat offered in Germany but , quite frankly, they are not needed - which is why I mentioned it). You shouldn't need to cut into any cables.
Which model 2000 do you have? - D, S, ST, STC? If one of the first 3 you should have a Unibox with the controller and an external temp sensor can be connected to the unibox. If STC it will connect to the 18 pin main ecu plug positions 8 and 9, ( I can make you a lead up to 6.5m with an external temp sensor), there should be a fixed 610 Ω resistor there currently.
 

Alan Watts

Member
I have a Webasto HD Controller installed [airtop2kw], does the temperature sensor simply clip into the HD controller? Is this the same as the Unibox?
 
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oldiebut goodie

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No - the Unibox is an interface between the older ST models and other heaters and the controller - it enables the Multicontroller to talk to the older heaters. The only possible connection to a Multicontroller is the standard W-bus connection, there is no facility for adding anything to the controller. ( The connection under the rubber plug at the bottom is for hooking up to a computer for diagnosis)
You don't say which model 2000 you have - there are 4, the original Air Top 2000, the Air Top 2000S, the Air Top 2000ST and the latest model the 2000STC ( excluding the Air Top 2000 Evo which is a special model for Volvo and Renault trucks, not on general release)
If you have the STC - as above.
 

Alan Watts

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thanks for the quick response.

It is the Air Top 2000ST. Would it be possible to add functionality of temperature sensor?
 

oldiebut goodie

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Yes - it is the same plug on the ST and STC and the same pins 8 and 9 that it connects to. It is only very recent ST models that will be able to use the Multicontroller. The manual says heaters after 04/2015 shouldn't need the Unibox.
The Multicontroller is a strange beast in that it does have a temperature sensor built in but that information doesn't appear to be transmitted to the heater to regulate the heat! As people have found.
This is what the manual says about it:
Integrated temperature sensor
To monitor the control devices system a temperature sensor is integrated into the MultiControl.
Mainly this sensor secures the device from damage but it can also be used to show the actual
temperature on the display. It is adjusted via the service menu. In case an external temperature
sensor is connected, the integrated temperature sensor is overruled.
 

Dave Leaning

New Member
Oldiebut goodie
If you would be kind enough to answer a couple of questions please.
How easy is it to add the components to make the Webasto 2000 controlable from my phone? I read it is possible and I fancy the idea of being able to run the heater before I got out to the van on frosty mornings. I currently have the basic controller.
And, what extra components would I need?
Mant thanks

Dave
 

oldiebut goodie

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Oldiebut goodie
If you would be kind enough to answer a couple of questions please.
How easy is it to add the components to make the Webasto 2000 controlable from my phone? I read it is possible and I fancy the idea of being able to run the heater before I got out to the van on frosty mornings. I currently have the basic controller.
And, what extra components would I need?
Mant thanks

Dave
Depends upon which 2000 model you have.
https://www.butlertechnik.com/webas...ced-smart-phone-remote-control-9032141a-p1826

Out of stock at present, not cheap either @£450! Only for the Air Top 2000STC model though. There is a cheaper model @£350 but I don't know what the benefits are of having the more expensive model. You are supposed to mount the antenna at the top of the windscreen for good reception but wouldn't be possible if you have a heated windscreen I am given to understand. It would be cheaper to change to a timer also.
A lot cheaper to walk outside!
Theoretically a Telestart T100 @ around £270 should be able to be used on a heater that has W-bus signalling like the ST and STC, this would be good for 1000m but would need testing first to see if they are compatible. The Telestart T100 is designed primarily for the water parking heaters although I have just fitted one to my Air Top Evo40.
It is possible to use one of the cheap ebay remote relay switching controls for a couple of 100 metres to simulate the pressing of the heat button on the controllers for older heaters if you are handy with soldering and wiring.
 

oldiebut goodie

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Webasto Air Top 2000 ST STC temperature sensor | 1319842A | 9005004B

is this right @oldiebut goodie

for example i buy this external sensor and cut into the wires like shown?
Yes, that would work that way.
I prefer to do it by removing pins 8 and 9 on the ecu plug though and making the connection there. ( that way you can just replace the pins if you wish to revert to the original and not have to rejoin wires) Although this would mean that you have to access the heater to unplug the loom though rather than accessing it near the controller.
 
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