DIY Electric Car Forums banner

MEA DEA RM4 Heater stopped working

6140 Views 20 Replies 6 Participants Last post by  Hans
The MES RM4 heater in my car has stopped working. When I switch it on I can hear the pump running. The pack voltage can be read at the unit so I know it is live from the battery pack. There is another pair of wires that go in to the heater and this goes to 12 volts when switched on as well. The heater is just not drawing any power from the main pack. Does any one have any ideas on what I should check next?


21 - 21 of 21 Posts

· Registered
9 Posts

To bad to hear you have a problem with your heater.
Mine is still working fine luckely.

I had a problem to get it working, searching for the right PWM-controller trims.
A person from Eberspacher told me:
"You have to exceed the 70% limit for the high level to be recognized. You can go all the way up to battery voltage.
The PWM signal can go from 0 to Ukl 15.
The low level is detected below 0.3* Ukl 15 and the high level is detected above 0.7* Ukl 15."
It is something what also is described in the documents.
I got some help from a specialist in electronics who helped me trimming the PWM-controller, and it all worked fine since that time.
I now know that it is very specific to have the right PWM- cycle.

But, you had it working for a period? and the heater stopt overnight?
  • Was ther enough coolant (overheating; no air bubbles in the line; fuse damaged);
  • Is the pump working fine?;
  • Do you have a flow in the coolant system (no line's or the heater clogged?);

When all the "input's" are correct, there could be something wrong with the electronics of the heater.
Try to find someone who can test the electronics of the heater, or find a heater from a demolition car (just for testing the "input's")
Otherwise I also shouldn't know where to start looking.
Hopefully you find a solution.
Keep me posted, because...You never know, next time I will be the one with questions about a disfunctioning heater 😉

21 - 21 of 21 Posts