Truma heater fan issue

Silver-Fox

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it seems my woes continue :rolleyes:

The Truma heater fan tries to work, runs a bit slow goes quick the stops.

Truma itself is working fine on hot water or combined water and heating.
The fan spins freely by hand so bearings not an issue.

I’ve done a search on here and google but can’t find any info.

Anyone on here got any pointers as to a fix.

Thanks
 
OP
Silver-Fox

Silver-Fox

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I’m not on hook up at the mo so just on gas.

For some reason I presumed the fan worked on 12 V don’t know why.
 

Lenny HB

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I’m not on hook up at the mo so just on gas.

For some reason I presumed the fan worked on 12 V don’t know why.
It does.
If it's spining feely and not full of dust and muck it is probably the control circuit on the PCB. I don't think they repir them they just sell you a new PCB for around 300 quid.
 
Jun 4, 2016
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Yip the fan does go on 12v, but on mine the fan"roars" when it's on gas, once the boiler has heated up, where as on electric it's more lackluster
 

Lenny HB

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Yip the fan does go on 12v, but on mine the fan"roars" when it's on gas, once the boiler has heated up, where as on electric it's more lackluster
That's because the electric is so low power on full chat it would be blasting cold air round the van.
 
OP
Silver-Fox

Silver-Fox

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Yip the fan does go on 12v, but on mine the fan"roars" when it's on gas, once the boiler has heated up, where as on electric it's more lackluster
Ahh got you.
Yes it just about gets to the roar and quits grrrr.
 
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Silver-Fox

Silver-Fox

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It does.
If it's spining feely and not full of dust and muck it is probably the control circuit on the PCB. I don't think they repir them they just sell you a new PCB for around 300 quid.
Would it still try and run the fan do you think if the circuit is nfg on the pcb

I wonder if I could just fire a supply straight to the fan bypassing the pcb
 

Lenny HB

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Oct 18, 2007
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I wonder if I could just fire a supply straight to the fan bypassing the pcb
Assuming it's a 12v and only 2 wires going to it, should run at full blast with 12v on it. But if it has more than 2 wires it may have internal control circuits then not wise to.
 
OP
Silver-Fox

Silver-Fox

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Assuming it's a 12v and only 2 wires going to it, should run at full blast with 12v on it. But if it has more than 2 wires it may have internal control circuits then not wise to.
I’ll have mooch around it tommorow and see what’s what.

Then it will be the fridges turn as that’s not firing up at first asking.

Still no one said motorhoming was cheap or easy :rolleyes::)
 
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Silver-Fox

Silver-Fox

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That’s a good start it’s absolutely p****** down at the mo so the fan can wait a while :rolleyes:
 
Feb 5, 2014
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Silly question: it's not the thermostat set low so that the fan cuts out is it?

Mine works happily 95% of the time but SOMETIMES it refuses to throw out hot air, even though the thermostat APPEARS to be reasonably high. I turn it down then turn it back up and "woosh".

[Much cheaper than a new pcb!]

Good luck - Gordon
 
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Silver-Fox

Silver-Fox

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Silly question: it's not the thermostat set low so that the fan cuts out is it?

Mine works happily 95% of the time but SOMETIMES it refuses to throw out hot air, even though the thermostat APPEARS to be reasonably high. I turn it down then turn it back up and "woosh".

[Much cheaper than a new pcb!]

Good luck - Gordon
I tried turning the boiler stat for the heating up and down but it made no difference :rolleyes:

I much prefer problems where spanner’s are involved.
Elaetric/electronics I find a pain in the rump :mad:


Thanks for the suggestion though (y)
 
Feb 15, 2016
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Are you using it on auto or manual? You should be able to control the speed on manual whereas on auto it will decide what it wants to do.
We currently have a different problem with ours, on electric the thermostat doesn't work, I believe this is likely to be down to the control panel as well :(
 
OP
Silver-Fox

Silver-Fox

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image.jpg

This is the only controls I have.
It’s an older system and no separate controller for fan speed.

I’ve just turned the system off and the fan went into cool down mode.
This blows hot air through the heating tubes.
So the fan definitely works.

Unfortunately they have fitted the boiler in such a way you can’t get the top of the electrical box off :rolleyes:
 
Feb 17, 2019
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I've actually got the fan off mine at the moment investigating a problem which appears to be that when the casing/frame of the motor gets hot something expands enough to stall the motor as if something expands so much that it doesn't want to turn freely any more.
 
OP
Silver-Fox

Silver-Fox

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Yes you can, you just have to dismantle the van first. :rofl:
Thanks @Lenny HB I knew I could rely on you :rolleyes:

I've actually got the fan off mine at the moment investigating a problem which appears to be that when the casing/frame of the motor gets hot something expands enough to stall the motor as if something expands so much that it doesn't want to turn freely any more.
Mines turning freely even when the boiler is too hot to touch.
And it runs a cool down when turned off and hot.

This is doing my nut in :mad:
 
Aug 31, 2009
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Carthago C Tourer T150
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Our Truma combi 6 is doing the same thing. As soon as the heater fan moves up into "turbo" mode it cuts out. If we heat the water first then switch to water and heat it gets up to temperature OK, but if we then turn the water off it goes into cool down mood for a few minutes but the heater will then stay on. Our local Truma engineer is going to look at it when we get home, he thinks it could be an overheat sensor causing the problem. This is on gas only by the way, it works OK on just 220V.
 
OP
Silver-Fox

Silver-Fox

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Our Truma combi 6 is doing the same thing. As soon as the heater fan moves up into "turbo" mode it cuts out. If we heat the water first then switch to water and heat it gets up to temperature OK, but if we then turn the water off it goes into cool down mood for a few minutes but the heater will then stay on. Our local Truma engineer is going to look at it when we get home, he thinks it could be an overheat sensor causing the problem. This is on gas only by the way, it works OK on just 220V.
Will be interesting to find out what fixes it.
Would appreciate you posting the outcome.
 
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