However reliable and efficient the Eberspacher Airtronic D4 heater is, one problem that can occur is that it can get sooted up. It seems that under certain conditions (perhaps when running on certain quality of red diesel) soot can start to build up in the heater. Eventually the heater will have so much soot in it that it can’t function anymore.
The heater will go through the startup cycle but soon cut out when it can’t keep the flame alive. While in the startup cycle and when the burner is trying to burn, only a small amount of air will go through the combustion chamber and at the exhaust there will be just a gentle stream of smoke coming through.
However, if you have this problem and found this page – fear not – we will explain how to fix it. The Eberspacher Airtronic D4 heater is easily servicable and it doesn’t require a lot of skill, time or effort to fix this problem.
First you need to unplug the unit – unplug the electrical connection, air-ducts, exhaust pipe, and fuel line. While doing this kind of job it is really helpful if you have a good head torch as you can use both hands to do the work.
Ultralight LED head torch
Once you have removed the unit you need to remove the outer casing. Remove the top plate by undoing the plastic hinges. Then, in order to get the actual heater out from the bottom plate you need to remove the rear lid. Use a screwdriver to push the catches while carefully levering the rear lid out of the bottom plate.
Now you have got the heater separated from the outer casing. If your heater is coked up you will probably see the soot built up just at the exhaust pipe.
Next you need to remove the electric control box and the blower motor. Unscrew the single torx-screw that fixes the electric box, and then unscrew the screws the hold the blower motor to the body of the combustion chamber. Be careful not to damage the seal that sits between the blower motor casing and the combustion chamber.
You will now need to remove the glow plug (connected with a brown and a white wire) and remove the torx-screws from the plate that holds the glow plug to the combustion chamber.
Open up the chamber and remove the soot that has been built up.
That is all that is required once the unit has been put together again. We would suggest running the heater on white diesel for a while as this will help to remove any left over soot in the heater.
