Bosch WTA4107 not heating

[PhilA]

Hi,
I hope you can give me some guidance please. I’ve had a look round for similar problems and tried what was suggested but I can’t determine the problem.
Our tumble dryer is a Bosch WTA4107GB/01, about 8 years old.
It runs fine, but there’s no heat. I’ve checked that the outlet is not blocked, taken the back off and measured resistance of the element (18.4 ohms, so I think that’s OK) and of the 2 thermostats I can find (0.2 ohms each, again I think that’s OK). I then took the top off and checked all the connections behind the controls and the PCB mounted behind them (with the power off!). When I tried the machine again it worked once, but then stops heating. I’ve been round everything again with the same results.
If anyone knows of other things that can fail on these machines or suggestions for what else I can test I’d be grateful.
I notice from other posts that some machines have 3 thermostats – is mine one, and if so where is the thermostat that I can’t see(!)?
Thanks in advance for any help you can provide.
Phil

[Martin]

Re: Bosch WTA4107 not heating

2 stats on the heater duct and the 3rd located on the front exhaust duct.

[PhilA]

Re: Bosch WTA4107 not heating

Thanks Martin. That one checks out ok as well.
I have found that waggling the connectors on the control board and switches at the top of the machine gets it running for a few loads but then it stops heating and needs doing again. I can’t find any connection actually loose though.
Any other ideas gratefully received!
Phil

[Martin]

Re: Bosch WTA4107 not heating

You’re gonna have to check those wires more closely then I reckon.

[PhilA]

Re: Bosch WTA4107 not heating

Still trying – I have to wait until the fault reappears each time which can be a few days but it’s still there.
The problem seems to be with the control board that sits at the top of the machine on the right hand side – the one with relays on it, not anything behind the controls. I can’t see any burnt or damaged terminals in the connector, nor any dry joints, cracks in the board or components which show signs of heat. That may be as much to do with my eyesight as anything else though.
Do you know if the board is available as a part and if so how much it costs please?

[Martin]

Re: Bosch WTA4107 not heating

Available on the Bosch spare parts website, very expensive.

[PhilA]

Re: Bosch WTA4107 not heating

Wow, yes it is. I’ve just looked it up. Time for a new machine I think. Thanks for your help over the past few weeks.

[Author]

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