Webasto AT 2000 - Temperature Sensor? How Does It Work (as In Setup With Controller Etc)
There is no thermostat unless you are using a Multicontrol.
See my post here: Webasto diesel heater control question.
See my post here: Webasto diesel heater control question.
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.
Do you know what model Multicontroller you have as there are several flavours and have more or less functions in them.
I have cross posted this to the other thread.
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.
Do you know what model Multicontroller you have as there are several flavours and have more or less functions in them.
I have cross posted this to the other thread.
Last edited:
This is some of the blurb from the HD instructions ( shows that it is the internal temp sensing that is used):
Webasto MuiltiControl HD for Thermo Top water & Air Top EVO air heaters
please note - Extension harness required (9031988A) when using with non RV specific Air Top 2000 STC
The NEW Heater MultiControl HD from Webasto
• Programmable Timer with Quick start button
• Heating or ventilation
• Active 7 day forward planning
• Manual heater control & digital temperature adjustment of your Webasto Heater
• Surface mount installation
• Suitable for both 12v or 24v heater versions
Simply turn the heater on, adjust the set temperature and leave the
rest to the heater's automatic temperature regulation
Webasto MuiltiControl HD for Thermo Top water & Air Top EVO air heaters
please note - Extension harness required (9031988A) when using with non RV specific Air Top 2000 STC
The NEW Heater MultiControl HD from Webasto
• Programmable Timer with Quick start button
• Heating or ventilation
• Active 7 day forward planning
• Manual heater control & digital temperature adjustment of your Webasto Heater
• Surface mount installation
• Suitable for both 12v or 24v heater versions
Simply turn the heater on, adjust the set temperature and leave the
rest to the heater's automatic temperature regulation
Arf
New Member
Just read your post with interest. I've had the same air top 2000 stc heater recently installed in combination with the 9030910D multicontoller. The Webasto air heater has been mounted internally.
I used it for the first time last night and had the temperature set on the controller to 18 degrees celsius on an infinity setting - which I thought would be comfortable to try it out. I was also under the impression that the multicontoller would act as a house central heating thermostat monitoring and regulating the heat on/off. The heater seemed to not cut off at all (after about 45 minutes) and my seperate internal temperature gauge (which is fairly accurate) was showing 23+ degrees and rising in the van (we were starting to feel uncomfortable at this point!). I played around with the heater and adjusted the temperature on the multicontroller to 12 degree celsisus. After doing this, the heater started to make less noise and became fairly quiet (the fan seemed to be the only thing that was on). The air that was being kicked out of the airtop was cool; therefore I thought the unit was recirculating air. The temperature in the van dropped to an acceptable level (approx 20 degrees celsius) and was regulated thus - with the temperature on the multicontroller set to 12 degrees celsius! Therefore, my conclusion is that #oldiebut goodie is correct in his observation that the temperature is monitored by the heater itself and not by the multicontoller OR that the multicontoller that I've got is faulty (which I doubt). So from this, it appears that I too require an external temperature fitting to get an accurate thermostatic operation or I'll just set the multi contoller to 12 degrees and run it like that!.
I used it for the first time last night and had the temperature set on the controller to 18 degrees celsius on an infinity setting - which I thought would be comfortable to try it out. I was also under the impression that the multicontoller would act as a house central heating thermostat monitoring and regulating the heat on/off. The heater seemed to not cut off at all (after about 45 minutes) and my seperate internal temperature gauge (which is fairly accurate) was showing 23+ degrees and rising in the van (we were starting to feel uncomfortable at this point!). I played around with the heater and adjusted the temperature on the multicontroller to 12 degree celsisus. After doing this, the heater started to make less noise and became fairly quiet (the fan seemed to be the only thing that was on). The air that was being kicked out of the airtop was cool; therefore I thought the unit was recirculating air. The temperature in the van dropped to an acceptable level (approx 20 degrees celsius) and was regulated thus - with the temperature on the multicontroller set to 12 degrees celsius! Therefore, my conclusion is that #oldiebut goodie is correct in his observation that the temperature is monitored by the heater itself and not by the multicontoller OR that the multicontoller that I've got is faulty (which I doubt). So from this, it appears that I too require an external temperature fitting to get an accurate thermostatic operation or I'll just set the multi contoller to 12 degrees and run it like that!.
When I sell a heater I tell people that the controller isn't a thermostat and that the heaters measure the temperature of the air drawn into the heater. Of course, normally, the heater receives the air to be heated from the lower regions of the vehicle/vessel so it is not going to get warm air for quite a time by which point anyone sitting or standing is sweltering. The best way is to set the rheostat so that the air at the midheight point of the area which is a comfortable setting and use that as the norm, as you have discovered. The multicontrollers lead people into thinking that they are thermostats by having temperatures to set them at which bear no relation to what the human body perceives.
If you want to get it to work with these controllers acting more like a thermostat using the set temperature you do have to add the remote temperature sensor - this overrides the one that is internal to the ecu in the heater.
If you want to get it to work with these controllers acting more like a thermostat using the set temperature you do have to add the remote temperature sensor - this overrides the one that is internal to the ecu in the heater.
thanks @oldiebut goodie - very useful info!
Ramvandweller
New Member
@oldiebut goodie this has been very useful! I am having the same issues with my airtop 2000stc, using the multicontrol. There is almost no temperature regulation using the internal temp sensory at the cold air inlet so I just bought the remote room temp sensor. looking at the system wiring diagram that came with the heater, i can see the plug positions 8 and 9 that you are talking about. Before cutting wires, I want to confirm exactly which wires they are. Do you remember what color they were? Any other information about the actual installation process of the remote temp sensor would be hugely appreciated as I feel a bit in over my head but still weirdly optimistic! thank you in advance!
The temp sensor is in the intake air inlet (unless you have the separate sensor) we find setting the temp at around 13deg on the controller is just right. Our inlet is in the drivers door step, so the air drawn into there is much cooler than the air in the main body of the van.
Post above has missed the point of your query!
Theroretically they should be black with a blue stripe but there are numerous colours used in practice! Which is of no help - you will need to unplug the loom from the ecu to be certain what you have.
If it has a ST loom instead of a STC one it could have one black/blue and one yellow!
You can see 8 in the middle row of small holes on the left, 9 is the next one to the right.
You should be able to pick up the correct wires further up the loom but you need to remove the 610Ω resistor that should be there bridging the two wires. As to the exact position of that resistor in the loom - it may be at the external end of the loom handily marked or it may not. This is why I remove pins 8 & 9 and wire the external sensor direct to the plug instead, so much easier!
Here is a reply that I gave concerning the positioning of the external temp sensor:
Mid height is the best position for all round performance. Position in the van should be away any source of a draught and also sunlight. Sunlight will warm it up quite quickly so not where the sun can come through any untinted windows. You also don't want it to be too close to the heat source outlet path. It may be easiest to not make a permanent fixing at first and just tape it in place until you get the heat control that suits you best with your van layout.
Theroretically they should be black with a blue stripe but there are numerous colours used in practice! Which is of no help - you will need to unplug the loom from the ecu to be certain what you have.
If it has a ST loom instead of a STC one it could have one black/blue and one yellow!
You can see 8 in the middle row of small holes on the left, 9 is the next one to the right.
You should be able to pick up the correct wires further up the loom but you need to remove the 610Ω resistor that should be there bridging the two wires. As to the exact position of that resistor in the loom - it may be at the external end of the loom handily marked or it may not. This is why I remove pins 8 & 9 and wire the external sensor direct to the plug instead, so much easier!
Here is a reply that I gave concerning the positioning of the external temp sensor:
Mid height is the best position for all round performance. Position in the van should be away any source of a draught and also sunlight. Sunlight will warm it up quite quickly so not where the sun can come through any untinted windows. You also don't want it to be too close to the heat source outlet path. It may be easiest to not make a permanent fixing at first and just tape it in place until you get the heat control that suits you best with your van layout.
Ramvandweller
New Member
okay, i understand what you're talking about now. This next question might be stupid but forgive me, electrical is not my strong skill. If i can just cut the wires going to pins 8 and 9 and re-terminate them like it is recommended from webasto, which end of those wires am I using to plug in to the external temp sensor? the wires coming from the ECU or the wires going to the ECU? I don't think I am skilled enough to remove pins 8 & 9 and wire the external temp sensor directly to the plug... i'm sorry I am asking so many specific questions, I have found webasto technical support in UK to be quite unhelpful.
Pull the plug from the ecu - bend the flat slightly away from the ecu and there is a hole in the flat, use a screwdriver in that and lever against the ecu casing and the plug will come up and out. Snip off the cable tie that holds the wiring to the flat part of the plug then it is easier to manipulate the wires. Find the 2 wires from 8 and 9 and cut them high up close to the loom covering/ rubber grommet as far away from the plug as you can so that you have enough spare to solder the 2 new wires to them, solder the remote sensor wires to the wires coming from the plug, don't forget to put heatshrink on first ready ( feed the the remote sensor's wires through the rubber loom grommets in the floor and the heater first), there is no particular orientation to the wires. Then cable tie the wires back to the flat of the plug and re-insert in the ecu.
Don't worry about the cut ends going into the loom - they have no connection to anything now.
Don't worry about the cut ends going into the loom - they have no connection to anything now.
Last edited:
Ramvandweller
New Member
wow, this was incredibly helpful. thank you!
@oldiebut goodie & @Ramvandweller are we talking about this: Webasto Air Top 2000 ST STC temperature sensor | 1319842A | 9005004B
i was going to fit this as discussed with oldie, but am now having doubts - can i do as indicated on my link?
when i look at the picture, i must say its a bit strange - yellow black to white black..is there a sense to the cabling?!
i was going to fit this as discussed with oldie, but am now having doubts - can i do as indicated on my link?
when i look at the picture, i must say its a bit strange - yellow black to white black..is there a sense to the cabling?!
No, no sense! That is why I said above that the wires colours may not be as indicated in the circuit diagrams. If the wires are present at the end of the loom it is easiest to use them rather than having to access the heater - you can see the bulge in the loom where the resistor is situated. I think that they just use any colour wire that is to hand at the time! On numerous Webasto looms there are inconsistencies in the colours when compared to the standard circuit diagrams, usually found when a heater loom is produced for the vehicle manufacturer to suit their wiring scheme needs. I quite often have ST looms that do not have the resistor or sensor in at all and have to add one. I have only had to deal with a few STC looms and only one had the resistor already present.
Sorry to drag up an old post..
I have an Air Top 2000 STC with the multicontroller.. I have fitted the Thermo Call TC4 module so I can control it remotely. Just had the external temperature sensor turn up as the mobile app uses this to report temperatures when they go above or below a temperature..
I wondered how you got on with fitting the sensor and if it made the heating more accurate?
Install guide on the workshop manual.
I have an Air Top 2000 STC with the multicontroller.. I have fitted the Thermo Call TC4 module so I can control it remotely. Just had the external temperature sensor turn up as the mobile app uses this to report temperatures when they go above or below a temperature..
I wondered how you got on with fitting the sensor and if it made the heating more accurate?
Install guide on the workshop manual.
Last edited:
