Webasto heater problem

[shamrock]

Knowing that there is a wealth of expertise on this forum, I've searched but to no avail, so maybe someone can suggest a next step.

I have a Webasto Airtop 2000 24v heater - it's an ebay ex-truck cheapie so not too much lost if it's a dud. I connect it up according to the technical manual from the Webasto website. When I turn on the rotary switch, the green LED on the switch lights up (solid, not flashing) and the fan starts.

That's as far as it goes. 20 mins later, the fan is still running but it's gone no further.

The fuel pump works fine when pulsed with a fly lead, but never starts to tick from the heater. The heater has 24.7v when running, so it's not low batteries.

Suggestions?

many thanks

Nick

 

[sailorman]

air-lock in delivery pipe ???????
try disconnecting the heater end to bleed it with pump running

 

[FullCircle]

Do you have the short stubby thermostat under the cover on the unit, or the long one on thin wire leading back to the cabin? (may lead to the switch panel to a slide adjustter, which needs to be centred)
If you have the stubby one, its possible that where you have mounted the unit fools it into thinking the area is hot enough and does not need heating.
If no flashes, then no malfunction, and that includes temp sensor dud, fuel supply, firing sequence, the whole lot.
I have had to wait over 30 minutes for mine to settle down and start delivering again.
Set it running and leave it.
If you have a vhf, place it near the unit, you will hear the ticking of the dose pump and firing sequence when it finally goes.
Ensure you have the rocker switch which has a flame and a fan on it, so that the flame is pressed in, or it will never start. If you have a red or yellow wire connected, just leave it off.
I take it you have the blue white black and going to the 4 way plug correct?

If no joy, speak to JPC Webasto in Norwich, they are brilliant.
And buy the Combination timer, its brilliant.

 

[David2452]

Check the glow plug and overheat sensor resistances are within perameters with a multemeter, check the fuel pump conectors with a multimeter for pulses. . above advice assumes AT2000 diagnostic model. You say the fan runs but the pump is not ticking, if not then you may have a board problem particularly as you seem to have a constant light instead of a fault code flash. Note that any fault in the glow plug and several other components will prevent current reaching the pump as they are all wired together in series as safety measure. Another posiblity is if the heater came from a truck carrying DG then the wiring may need modification as there are extra auto cutouts to the fuel pump on models wired for TRS. Let me know if you need a wiring diagram & I will email it if you give me the serial # and precise model # from the installation label

David.

 

[shamrock]

David, that's great help - will PM you with detail of the heater. I'm away now until Sunday but have the heater set up on the bench and will get the MM on it when I'm back. I don't think it came from a DG vehicle as it doesn't have any of the extra wiring shown in the manual, but I could be wrong.

I'll report back to the forum on progress. Thanks all.

 

[mikejames]

BTW the version of the Airtop 2000D (year 1997) which I have works on 12 volts as well as 24 volts. There is no separate model for 24 volts

It has two voltage bands , one centred on 12 volt battery voltage and the other centred on 24 volts over which it works.


If there was a fuel supply problem then the LED would blink as it failed to ignite the fuel.

More likely is a wiring problem around the temperature setting control variable resistor or with the temperature sensor (thermistor).

On mine this temperature sensor is separate from the rotary dial heater control on a long wire. On a warm day the heater may not come on anyway, just the green light and the fan, as I think the highest set point is in the high 20's degrees C.

I am not sure that the heater can actually distinguish between an extremely 'hot' temperature sensor and not having one at all. The component used goes higher resistance at high temperature.

The worst problem I had was that the manuals are translated from technical German into English and seem to be intended for somebody who has intimate knowledge of German goods vehicle regulations.

But I find the diagnostic extremely good at finding out what the problem is : I excercised many of its modes while messing up an installation. http://www.hamble.demon.co.uk/heater.html

 

[dog]

If its like mine, there is a little switch next to the rotary control with a flame symbol against one position. The 3500 units are also capable of running as fresh air only with no heat. I have on several occasions hit the switch by accident and wondered why no heat..... not sure if the same for the 2000 model