Ml 270 Cdi Face Lift Heater Not Working.

[dibdib]

ML 270 CDi face lift. My heater system is not working and the rear heater fan I have disconnected, because it runs continuously when the ignition is turned off, and will only stop when the battery has gone flat. The front heater motor will only work on fan speed 3, even when the dial on the heater control panel is at 0. Also the glow-plug light stays on continuously even though all the glow-plugs and timer relay have been replaced.

Can anyone help?

 

[psmart]

The Glow-Plug light staying on all the time is indicative that a short circuit has blown a fuse inside the composite relay (a combination of Relay contacts and electronic processing components). Could possibly be that a short circuit exists somewhere on your glow plug lines that has taken out the old and new relay. If you pull the relay apart (old one preferable) you can identify which glow plug has a short by the fuse link which has blown.

Not sure on the heater circuit but you can get it plugged into a diagnostic computer at your local dealer or indie as the EAM/AAM controls the heating circuit and it will report the fault code (hopefully).

Cant be more help, hopefully someone else will have experience of heating circuits.