If the webasto heater is working the entire time on a 250 mile journey then I would suggest there is either a fault with the signal from the ecu to webasto or an issue with your ECT sensor, thermostat on its way out, fans constantly on? Does the temp gauge sit approx half way after a good drive?? If you can get a scanner plugged in and read temp when you have been driving for a few miles to fully warm up the engine.
It should improve engine performance and mpg in colder weathers due to rapid warming of the engine coolant, however if you have the blowers on full it won't be as efficient. But logically speaking it won't improve economy that much anyway as you are using extra diesel on top of running the engine to warm the coolant It is designed mainly as an oil burning comfort device.

 

royal100805,

- it will I posted my result figures on this forum somewhere ages ago my friend
- it will, it will output the same efficiency - just takes longer - engine first - cabin next & last

The squiggly light just means [monitoring] on, not on and pumping out heated water. Try stopping for fuel or just switching the engine off, the secondary heater and its squiggly light will not come on. If the engine or the cabin cool enough the Webasto will come on, that's its job, there's an internal cabin resistance thermistor. If the heater is not temperature set to automatic its not automatic. I confess I've no idea if you 'fiddle [earlier comment] with the non-auto controls.

fragmented,

The heat needle should be around a half in the worst of the weather. The Webasto fuel consumption and amperage draw is fractional, like your domestic iron or oven once it reaches thermostatic temp it turns up & down. The fan slows, the pump draws less fuel etc. The inside of a GV is a huge litre-age but should get to comfortable [see Leedsmans thread] in 15 minutes with the Webasto. If it doesn't maybe you do have a problem. If the wiggly lines bother you just pull the electrical connector as I said earlier. The Webasto is all 'on unit' logic - it works or it doesn't work, you can't even switch it on or off, all you can do is dial in an automatic temperature.

 

QinteQ I know you are very passionate about your comments but I do need to correct a slight mistake. The cabin heater as the name suggests is for heating the cabin to aid passenger comfort. It isn't put in place on this specific vehicle to aid in engine warming and improve fuel economy whether it happens to do so or not.
It gets it's cold supply coolant from the engine and fires up when temp drops below 15 degrees C. It then heats the coolant and sends it to the front heater matrix. Then after heat exchange back into the engine coolant cycle. Not ENGINE FIRST HEATER CABIN SECOND.

 

- agree, that's what I thought I said at 2am after watching a long movie
- maybe I should not make nocturnal posts while booting the puter down
- certainly having re read it I should have expressed it as engine first because :

The cabin heater [matrix] relieves the block. The big lump called an engine needs only to heat itself to the stat opening point. Conversely the fuel consumption would raise if the cabin heater was not used, precisely because the engine would stay cold for longer, its precisely because the hot cycled fluid from the cabin heater goes into the cold engine fluid raising the temp even faster, reducing the fuel consumption - yes its a cycle.

Did your cap's lock get stuck my friend

 

fragmented,

- almost everyone I've seen that do not work are user error, set it to auto and leave it - you can select high low but not manually set / choose fan speed etc
- pull the NEG battery cable for 15 minutes will do a soft boot of all the cars logic sets
- pull the connector underneath the car with the IGN ON will force a hard reset of the Webasto's own EEPROM

 

Thanks for the above suggestions I'll try them.

I have a two hour job in Penznace tomorrow - that's a 540ml round trip from the Midlands so I'll see how it goes.

Thanks

 

To avoid confusion for everyone, the cabin heater is the thing under the car called a Webasto, the controls for cabin heat should in this context be called 'climate control'. Mopar call the unit an a/c and heater control. the pic from ebay is rubbish but will do for this purpose, I might photograph my own {{edit changed pic}} and edit this post later so we are all on exactly the same page.



I've just run a test for fragmented. Mine is set to auto by which I mean the three toggle switches [high / low fan speed / passenger 60°C driver 60°C] but the fan speed and air direction ***** were not touched as they are controlled by the climate control[er], the unit was on and the squiggly lines were there. I travelled until the water temp was 1/2 and the cabin temp was about stifling. I then switched the unit off with the power [PWR] switch off and turned the IGN off. Turned the IGN on and stared the car, then switched on the climate control the squiggly lines were now not lit, and the climate control heater as expected worked ok with engine heat only and the Webasto turned off.