Webasto Heater Guru Advice ?

[Campervan_man]

Took a 2007 labelled Webasto 2KW heater off a Motorcaravan.
Fault :-
Rheostat Controller lights up when turned ON,
fan spins for 1 second and stops, light stays on.

Suspect 'Lock out mode.'

Tried disconnecting the 12V power for 10 seconds to reset then restart but same symptoms.
Also ran the engine then tried disconnecting and reconnecting heater after 10 seconds within 60 seconds.

Not stripped the heater down, just removed the whole kit.
It was fitted under the van and the exhaust pipe was 'intact'.

Any 'fix' advice ideas ?

 

[Late Starting]

It works on the balanced flu system = inlet pipe needs to be same length as exhaust pipe as far as I remember.
cliff

 

[Campervan_man]

Thanks Cliff.
It was fitted and working when the van was bought a year ago.
If I have time I will strip it down.
I've replaced the Webasto with a cheaper higher output Chinese Diesel Heater for now.