# Trumatic C4002 circulation fan



## Martin P (May 18, 2019)

Hi all
Has anybody replaced a circulation fan on a trumatic heater.
The motor on mine is marked 34000-64100-05.
These are getting harder to come by and a lot of suppliers marking them as discontinued. I found one which looks identical but it is marked as 34020-61300 rev 05.
The electrical plug on the wire tails from the motor is different so am wondering whether to cut the plug off and fit it anyway. 
I have emailed the truma service dept but they are not open till monday. I will wait as the motor was £130 so don't want to open the packet if I need to return it.
Just wondered if anyone on here had run into this
M


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## Martin P (May 18, 2019)

Just found the part number is for the truma combi heaters. It will be interesting to hear if the motor is suitable for the trumatics if motors for them are no longer available


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## witzend (May 18, 2019)

CCG 27292 Truma Combi C 6002 Fan Motor CaravanParts.co.uk

Truma Circulation Motor 34020-61300 - 34020-61300 Buy SECURELY Online

Don't know if you've seen these


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## Martin P (May 18, 2019)

witzend said:


> CCG 27292 Truma Combi C 6002 Fan Motor CaravanParts.co.uk
> 
> Truma Circulation Motor 34020-61300 - 34020-61300 Buy SECURELY Online
> 
> Don't know if you've seen these



Thanks for looking these up. Its a bit confusing. The first link shows a motor up to 2002, mine is a 2006 unit so probably not right.  The second is for the new motor I have got. I think it will be fine but a niggle in my mind is saying they may have changed the connector as it is incompatible. Then Im thinking that as it fits the newer combi perhaps that is why they have discontinued the motor with the part no I want as it just replaces it. I will probably just have to wait to hear back from Truma. I can't even compare with a test meter as the brushes in the old one are shagged


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## Martin P (May 18, 2019)

And a big cheer to motorhome builders who put them them together with no thought to maintainance and couldn't even fix the truma to the floor properly. 
I honestly think they are not designed to be fixable but are put together like a disposable lighter. Shocking


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## Martin P (May 24, 2019)

Here is the reply I had back from Truma uk

Thank you for your enquiry. The part nrs you’ve supplied are not the ones we use on our system, I think they are the German codes. The part nr you should have on the packaging is 34000-77300, however unfortunately these are now obsolete and we no longer have any available. You may be able to source one on ebay or similar.


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## Martin P (May 24, 2019)

Well I couldnt find one in stock so I sent this 

Hi Rachel
Thank you for your reply.
Will the fan motor from the truma combi 4 fit my trumatic C 4002?
Many thanks
Martin


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## Martin P (May 24, 2019)

To which I recieved this reply


No, I’m sorry it won’t


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## Martin P (May 24, 2019)

So I sent this

Thank you Rachel. How does it differ?. Maybe I can modify it?
Regards
Martin


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## Martin P (May 24, 2019)

Reply
We wouldn’t advise it, they are quite different, see below;We wouldn’t advise it, they are quite different, see below;

(They sent a parts diagram which showed the two different heaters but no detail of the motor which looked simillar)


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## Martin P (May 24, 2019)

So in the end I measured the the resistance across the terminals of both motors and they were pretty simillar.The new motor fitted straight on with no mods so I swapped the plugs over and it all seems to work fine. 
Better than having to scrap the the whole heater unit and buy a new one at 1400 quid .

If it blows up I will let you know
M


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## mickymost (May 24, 2019)

Martin P said:


> So in the end I measured the the resistance across the terminals of both motors and they were pretty simillar.The new motor fitted straight on with no mods so I swapped the plugs over and it all seems to work fine.
> Better than having to scrap the the whole heater unit and buy a new one at 1400 quid .
> 
> If it blows up I will let you know
> M



Obviously with the help Truma gave you they wanted you to fork out for a new system as you say about £1400.  Great you were able to figure out a fix for it at a load cheaper£££££££££


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## Martin P (Jun 7, 2019)

Bit long winded this but I think it might be useful to anyone with a trumatic heater with heater fan problems. 
Here is a fix for under a tenner


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## Martin P (Jun 7, 2019)

Checking the old fan motor revealed it was the brushes that had failed
Here are the closest I could find


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## Martin P (Jun 7, 2019)




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## Martin P (Jun 7, 2019)

Prize open tabs


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## Martin P (Jun 7, 2019)

The brushes are slightly too big. The 4.8 mm has to be reduced to 4mm. This is simple as they are very soft. A little rub on some 120 grit and it is a matter of seconds. 
The brush on the right has been reduced


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## Martin P (Jun 7, 2019)

The end of the motor with the old brushes. Dont lose the small pressure springs behind them


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## Martin P (Jun 7, 2019)

I cut off the old brushes leaving some of the braid. I shortened the braid on the new ones then soldered them together. I cleaned the old braid with some thinners first


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## Martin P (Jun 7, 2019)

To reasemble first fit the brushes back into their guides. Then jiggle the armature end of the rotor shaft back between the brushes. Hold the brushes back with a small screwdriver. Wiggle it in gently a little at a time. Dont lose any of the dhim washers. It sounds worse than it is. 

You have to put the rotor into the back motor bearing first then slide the whole lot into the motor casing and through the front bearing


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## Martin P (Jun 7, 2019)

Fold the tabs back 

Look out for the notch in the cover that aligns with the bump on the rear end.


One thought. Make sure that the brush braids are not so long that they will short on the motor casing.

When all back together connect to a 12v battery. White to pos black to neg. 
My motor spun up and ran a treat
Happy days

M


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## harrow (Jun 8, 2019)

As you say these carbon brushes can easily be filed down to make them smaller and agreed you need to watch out for any small springs before they disappear into the distance.

Another tip is using an old tooth brush to clean around the commutator.


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## Martin P (Jun 8, 2019)

harrow said:


> As you say these carbon brushes can easily be filed down to make them smaller and agreed you need to watch out for any small springs before they disappear into the distance.
> 
> Another tip is using an old tooth brush to clean around the commutator.



That is a good tip. Also having a good worksurface and taking it steady. Truma uk were not a great deal of help. Their answer would probably have been to buy a complete new boiler. For the sake of 5 quid it is worthwhile having a go at new brushes.


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## ari (Nov 19, 2019)

Hello Martin P ! I have C 6002 EH model and fan not working...  Whether that newer fan, 34020-61300 , worked well?





						Trumatic C4002 circulation fan
					

Hi all Has anybody replaced a circulation fan on a trumatic heater. The motor on mine is marked 34000-64100-05. These are getting harder to come by and a lot of suppliers marking them as discontinued. I found one which looks identical but it is marked as 34020-61300 rev 05. The electrical plug...




					wildcamping.co.uk


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## Martin P (Nov 20, 2019)

Well.
The fan worked well for a couple of trips , probably ten days use in all but we now have a circuit board fault. Whether it is linked to the old fan brushes burning out or the new fan compatability issues I couldnt currently say. Still looking for a fix for the circuit board. If you cant find the exact motor I would probably go the new brushes option. I am still looking to get our circuit board repaired but truma are very unhelpful about releasing circuit diagrams etc


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## ari (Nov 20, 2019)

Ok and thanks for the answer.


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## witzend (Nov 20, 2019)

There are firms which repair all makes of ECU,s perhaps one of them might look at your circuit board ?


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## Fitzykar (Nov 20, 2019)

Have the same problem and totally agree about Truma service support, they really want me to purchase a new unit. I'm going to see if i can find a company to do the overhaul of the motor


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## ari (Nov 22, 2019)

Martin!
Can you upload pictures from pcb boards on both sides? My friend is an electronics expert. He can look at them..


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## Martin P (Dec 2, 2019)

ari said:


> Martin!
> Can you upload pictures from pcb boards on both sides? My friend is an electronics expert. He can look at them..


Sorry. Missed this post.


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## Martin P (Dec 2, 2019)

Just had my Truma circuit board back from being repaired. Found a guy who specialises in these. (And other boards). His name is Richard from A and R electronic development ltd. Various board repairs are at various prices but mine was £50 for a full diagnostic check then £100 for the repair. The repair is guaranteed for a month against the same fault recurring.. 
Richard is pretty knowledgeable about Truma stuff which I found a bit of a lifesaver
Should anybody else need a Truma circuit board repaired here are his contact details.
Www.arelectronics.co.uk
Rsol@arelectronics.co.uk
01543 579302

I will post follow up when fitted at the weekend


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## Martin P (Jan 30, 2020)

Further to previous posts.
The fan motor from the later model truma does not appear to be a straight swap. 
After running for a couple of weeks worth of trips the Mosfet transistor on the board went again. The measured resistance of the two motors is different so presumably this is what took out the mosfet. Also a 1.6at slow blow glass fuse. 
I have now refitted the old fan motor which I repaired with modified brushes as per my earlier post. 
Mosfets to fit (I will post the id number later)   are available on amazon for about 10 quid for 5. I had a practice soldering and de soldering on an old circuit board and it was a fairly straightforward job once I had the right tools, solder and flux etc
Now running again. All fingers crossed


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## Martin P (Jan 30, 2020)

The mosfet is under this heatsink


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## Martin P (Jan 30, 2020)

Perhaps ought to say that this mosfet is of the normally open (off) type.
If it fails then it seems to go to permanently closed ( on)  The result of this is that failure results in the fan motor running permanently. Even if the heater unit is switched completely off at the thermostat


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## Martin P (Jan 30, 2020)

Mosfet no is IRF4905


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## Martin P (Feb 13, 2020)

Update
Now running ok
 It would seem that the motor from the later model combi is not a straight swap.
Measuring the resistance of both motors to compare , the original gives a reading of 2.6 ohms and the later gives a reading of 1.6 ohms. ( DC motors are a bit more complicated than this but it gives a guide).
Using current is volts divided by ohms
The original motor would pull 4.6 amps
The later motor would pull 7.5 amps
As the MOSFETs are happy up to about 5 amps it seems likely that the latter motor is what caused my circuit board problem.

To summarize
If you have a fan motor problem and a direct motor replacement is not available then the best repair would be to try replacing the brushes as detailed above several posts back


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## Toni M (Dec 20, 2020)

Martin P said:


> Update
> Now running ok
> It would seem that the motor from the later model combi is not a straight swap.
> Measuring the resistance of both motors to compare , the original gives a reading of 2.6 ohms and the later gives a reading of 1.6 ohms. ( DC motors are a bit more complicated than this but it gives a guide).
> ...



Hello from Finland. I broke my C 6002 EH fan motor from my motorhome and replaced it with a newer model motor that damaged the circuit board mosfet. The problem is that the newer fan motor gives a voltage spike to the mosfet when it shuts down and breaks the mosfet (IRF4095). Mosfet breakage can be prevented by installing a 51v zener diode in the mosfet. Since then, the new fan motor has been operating normally without breaking the mosfet.


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## Martin P (Dec 21, 2020)

Thats clever


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## gintrnis (Dec 20, 2021)

Toni M said:


> Hello from Finland. I broke my C 6002 EH fan motor from my motorhome and replaced it with a newer model motor that damaged the circuit board mosfet. The problem is that the newer fan motor gives a voltage spike to the mosfet when it shuts down and breaks the mosfet (IRF4095). Mosfet breakage can be prevented by installing a 51v zener diode in the mosfet. Since then, the new fan motor has been operating normally without breaking the mosfet.View attachment 90107


Hello,

please Toni M, save my soul. Just before holidayss, our fan broke up. Can You please tell which motor You bought, and i do not understand by the picture how did You connected/soldered diode.
Thanks for help.


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## SquirrellCook (Dec 21, 2021)

Toni M said:


> Hello from Finland. I broke my C 6002 EH fan motor from my motorhome and replaced it with a newer model motor that damaged the circuit board mosfet. The problem is that the newer fan motor gives a voltage spike to the mosfet when it shuts down and breaks the mosfet (IRF4095). Mosfet breakage can be prevented by installing a 51v zener diode in the mosfet. Since then, the new fan motor has been operating normally without breaking the mosfet.View attachment 90107


That back emf can sneak up behind you!


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## gintrnis (Dec 22, 2021)

SquirrellCook said:


> That back emf can sneak up behind you!


Please can You explain this, i do not understand.
Tnx


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## SquirrellCook (Dec 22, 2021)

When you remove the current from an inductor, the inductor try's to maintain the current.  Sometimes devices still in the circuit can fail to to the reverse high voltages that can be generated.  This effect for an armature can be worse. 

I don't expect this helped in any way.


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## gintrnis (Dec 24, 2021)

Does somebody know Toni M and can message him? I'm really desperate to hear from him, if it still works. I can burn mosfet, but i'm afraid to burn something more...
Thanks for help from anyone!

p.s.: Truma service offers me new one for 3000€ +work, but that's not an option for me right now, as well, i do not change all the installation because of new model.


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