# MEA DEA RM4 Heater stopped working



## brainzel (Jun 15, 2009)

Long ago but currently relevant to me.
My RM4 stopped a few weeks ago, same symptoms.

Anyone a fix?

Michael


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## Hans (May 10, 2014)

Hi, I had the same kind of problem with a MesDea RM4.
It wasn't possible to repair  (electronics in epoxy; i can send photo's).
I didn't like the on/off at the RM4. Alway using the full 4 kw when the heater was on.
I searched for a while for a replacement and found a Eberspacher Titronic CH-HV-60 unit.
An OEM-product, so no assistence from Eberspacher.
But with some research for the right PWM-controller I got a perfect heater now. And everything 'plug and play". 
A potentiometer (for the PWM-controller) on the dash, which is switched at 12v together with the pump.
So the heater can't run while the pump is off. Always first the pump and PWM-controller 'on' and then tuning the heater with the potentiometer.
This has also the advantage that the heater can be switched off, while the pump keeps running (The fluid stays hot for a while). 
For the expension I used a thermos (thermo bottle?).
One doesn't use the full 5 kw of the Titronic for defogging. 
But for a very fast warming up, one uses just a few little minutes full power, and after that put the potentiometer on 1/4 to 1/3 in stead of full-power.
Works great and saves the tractionbatteriepower.


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## mn23 (Dec 14, 2018)

Hello Hans,
I'm looking to try your solution of replacing an MES DEA RM4 with an Eberspacher heater. I found one on eBay. Could you provide a little more detail on what connections are necessary? I see you mentioned 3:
1. PWM
2. High voltage heater
3. 12V pump


What PWM controller did you use? Could you post a diagram of the connections? In the attached pictures there are three connections for the high voltage cable and three connections for the presumably low voltage.


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## Hans (May 10, 2014)

HI,

A few attachments with technical information of the titronic-CH-HV.60.
The PWM-controller I build with a friend in Luxembourg. Some components from Ebay, adding a transistor and a potentiometer, and it was done.
I could use the pump and connectors which were inthe car, so it was nearly "plug-and-play".
Hopefully you get your info out of the atachments. It should be enough to create the right PWM-controller.
BR
Hans


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## mn23 (Dec 14, 2018)

Hi Hans,
This is great, I'll take a look. My Titronic Eberspacher arrives tomorrow. I'll post my progress here. 



Just as an FYI this heater was used in the Fisker Karma, so there are some available on eBay if you use that search term.


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## mn23 (Dec 14, 2018)

Hi Hans, 

An additional question if you could. When you mention 

"For the expension I used a thermos (thermo bottle?)."
Could you be more specific? The RM4 had an expansion bottle of 1.5 or 2 liters, are you saying that the Titronic CH-HV-60 does not have a built in expansion bottle?


In gasoline vehicles there is an "overflow tank" and an expansion tank. Did you just use one of these tanks from a gasoline vehicle? What is the brand and specifications? Where did you place it in the system in relation to:
1. Inflow from the Titronic 

2. Outflow from the Titronic
3. Above or below the Titronic


Is the expansion tank pressurized?


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## Hans (May 10, 2014)

Hi,
Thats right, the Titronic does not have a built in expansionbottle. The Titronic is just a heating element.
And a closed system warming up, needs something so the warm fluid can expand.
You can use an overflow tank, because there is no real pressure.
Just like the cooling system of a petrol engine. It gives also the possibility to fill the system.
I used a thermo bottle which one uses for cool drinks or hot coffee.
The idea is that the heated fluid stays warm some longer than in a plastic bottle. No specific brand. Not specific above, under or near the Titronic, just in a place where it fits.
I placed is in the motor compartment "after" the heatercore in the dash.
So the pump sucks the "used" warm fluid out of the bottle, presses it to the heater, and the warm fluid out of the heater flows straight to the heatercore in the dash and flows back in the bottle. 
I preferred to have the bottle at the highest point of the system so al the air flows out the system in the bottle. No bubbles in the system when you fill it.
And the pump can't get overheated by hot fluid, because it gets the 'cooled down' fluid.
In my opinion the most efficient way to make the system.
After that you can isolate all hoses, and the expansionbottle (if you use a plastic bottle without isolation)

Hopefully this gives you some anwers.
BR Hans

I do have some photo's but at another PC. When I use that one | will sent them to you.


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## mn23 (Dec 14, 2018)

Hi Hans,
My understanding is that overflow tanks have pressure valves and expansion tanks do not. Therefore expansion tanks have something like 15 PSI or one bar. Overflow tanks fill up when the pressure exceeds the pressure valve setting. So does your system have pressure? I've attached a picture with 4 questions on it. I'll repeat the questions from the picture below.


1. Which side is inflow and outflow? I couldn't tell from the documents you sent.
2.Did you use the high voltage interlock? How did you connect it?
3. Is the system closed or open? If it is closed, the pressure increases when it heats up.
4. How did you connect the thermos bottle? Did you use a pressure valve?


Other than that, the PWM seems easy to figure out. Thanks for the documents.


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## Hans (May 10, 2014)

Hi,

1. The Titronic has no flow direction. So no inflow or outflow. Either end of the heater can be used as inlet or outlet.

2. I didn't use the hight voltage interlock. 

3. It's an open system, so no pressure valves.

4.The thermo bottle has an inflow just above halfway the bottle, and the outflow in the bottom. The inflow is also the highest point of the whole system, so airbubbels will come out the easiest way.

As attachment my heater incl the plugs. Both plugs were the same as my Mes Dea and pump plugs, so very easy to reconnect the unit.
Only the PWM gave me some trouble. But as I read your post, it will be easy for you to figure out.

The other attachment (jn600A) gives also some info (also about the inlet of the heater)

I thought I had a picture of the thermo bottle. But to bad just one where its build in the motorcompartment. You only see the top of it so not interesting.

The PWM-controller attachment gives the cirquit as we build on basis of a standard PWM-generator (from Ebay)

Hopefully I gave you the right answeres so you can get on.

BR Hans


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## mn23 (Dec 14, 2018)

Hello Hans,
I think I finally get it. I thought the Titronic was similar to the MES-DEA rm4 in that it had a pump as well. Since it does not have a pump, I'll just use the one off the RM4. So here is my plan:
1. Since the Rm4 has a working pump and is itself an expansion tank, I'll just keep it in the car for those two purposes.
2. I'll mount the Titronic after the outflow of the Rm4
3. I'll take the switched 12V that is currently going to the RM4 and connect it in parallel with the Titronic
4. I'll add a pwm controller and connect that to the switch as well.
5. I'll connect the pwm to the titronic as specified by the documentation.


Thanks for the additional info and all the information. This has been very useful. Out of curiosity, did you recycle the pump from the rm4 or have another pump?


I'll post my progress over the coming weeks.


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## Hans (May 10, 2014)

Hi,

I recycled the pump of the RM4.
I had not enough space for using the RM4-bottle and placed the Titronic somewhere under the hood.
The way you discribe it, looks like the most easy way. (if there is enough space ). 

BR
Hans


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## mn23 (Dec 14, 2018)

I always hate when I find threads that simply end without the end of the story, so I'll give an update. I pulled out the power electronics unit in my car to get access to see how much space I have in there to mount the eberspacher. It's pretty tight and mounting would involve taking off the dash. I'd likely have to pull the RM4 out, but I'm not sure what expansion tank I'd use or how to integrate. In the meantime, I found an RM-4 and am now testing it to see if it works. 

I'd really like the Eberspacher, but I think I'll save it till the new-old RM4 breaks then bite the bullet and pull the dash and mount it somehow.


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## Hans (May 10, 2014)

Do you have some photos? 
What kind of car you are working on?
I also had a very little space under the hood, but placed the Titronic under the hood, not behind the dash.


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## mn23 (Dec 14, 2018)

Hi Hans,
I'm working on a converted scion xb. 

I've attached some photos showing the current location of the rm4. The place I was thinking of mounting is circled in red. I'm not sure how I'd mount it without taking the dash off. Which i was trying to avoid. Did you mount it to the firewall?



In other news, I tested the other RM4 that I got and I think it's broken too. When you tried to repair, you said the electronics were in epoxy so unrepairable. If I take the two halves of the RM4 apart, can I put them back together without having it been broken? Did you determine a failure mode?


So I'll likely still pursue the titronic. Any pictures you can send of how your system looks under the hood or a diagram would be appreciated.


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## Hans (May 10, 2014)

Hi,
It took some time for an answere, but here it is.
I drive an "opel agila"/ "Suzuki Splash" as we call it in Europe.
Very little space under the hood, so I placed the Titronic (vertical, on a new subframe) in the same position as the old RM4.
I tried to make a photo of it, but it's difficult to see.
The titronic is behind/under the windowcleaner (blue cap). You can recognise the stainless steel bottle with the black lid which I use as reservoir for the heater circuit.

Seeing your photo's, I would try to use the bolt positions of the old RM4 to mount a new subframe for the Titronic. 
Only lower the position of the Titronic in relation of the position of the RM4.

The last photo (113525) is the bottom of the RM4 with the electronics in epoxy. (i tried to remove the epoxy, but thats nearly impossible without any damage to the electronic parts.

BR and all the best for 2020!!


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## mn23 (Dec 14, 2018)

And a long time for me to answer too. I'm moving, so I haven't had a chance to address the heater (and my power steering went out, so that has risen to the top of the priority list). Looking at your car, mine seems pretty roomy! Nice job on that. And I'm very jealous of your heat and power steering.

Thanks for finding those pictures. It gives me a better idea of the finished product. I like the idea of reusing the bolts for the RM4. But I'd have to make a new expansion tank as you have done. I'll have to do some research on that. Do you have a picture of it before you put it in the car?


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## Hans (May 10, 2014)

Hi,
I'll hope the pictures gives you an idea of the bottle I used. This was the first bottle (I wasted it because the hole in the wall was to low).
So a hole in the bottom (out flow), and in the wall (at the top; in flow) gives the right buffer.
Easy to check and fill up when necessary.
BR
Hans


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## ephemera (Jun 25, 2020)

And to add to this thread, if anyone is looking for the Eberspaecher heater, I have some for sale for just 500 Euro, just PM me.


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