Coolant Booster Heater Problem

Hey Everybody,

My coolant booster heater worked when I first got my sprinter last year but has since stopped working. Currently, I push the button on the dash and nothing happens. I used to hear the ticking of the igniter and then the heater would come on but now nothing. I checked both fuse panels for blown fuses but found nothing. Any ideas what could be causing the issue? I serched the forum but other than the fuse suggestion I didn't really find any solutions.

Thanks,
-Kris

The attached pdf has diagnostic procedures and info to help you understand how the heater is supposed to work.

Kris said:

Hey Everybody,

My coolant booster heater worked when I first got my sprinter last year but has since stopped working. Currently, I push the button on the dash and nothing happens. I used to hear the ticking of the igniter and then the heater would come on but now nothing. I checked both fuse panels for blown fuses but found nothing. Any ideas what could be causing the issue? I serched the forum but other than the fuse suggestion I didn't really find any solutions.

Thanks,
-Kris

Click to expand...

The ticking is actually the dosing pump delivering fuel to the heater. Assuming you have the aux htr option and you're trying to run w/o the engine running; if you don't hear the coolant circulating pump running, or the interior HVAC fan running, or the combustion air fan run momentarily, then you may have no power to the heater which is probably a relay issue. I don't at this point know where this relay is, but when mine has acted the way yours apparently does, I have been successful in getting it to run by tapping on the fuse panel under the driver's seat. Post back if you find that relay - the '03 service manual has info, but I haven't been able to figure out where it is as yet.

Hey Talkinghorse43,

Thanks for the quick reply. It's funny that you mention tapping the on the fuse panel under the drivers seat. I checked the fuses and fuse panels down there the other day and all of the fuses were taped into the panels. I wasn't sure why other than maybe the previous owner had trouble with them vibrating loose. I didn't spend too much time down there so I'll have a look again this weekend. I agree though, it seems as though I have no power to the heater itself. Thanks agaim, I'll post what I find.

-Kris