bosch 1200 classixx express not heating water

[Pw98]

Firstly I wish I had found this site before I ordered a new element!

The problem:
I put the machine on a wash program and it counts down in the digital display the remaining time. Once it gets to 1 minute it stays there forever.
The machine has filled and is in the wash cycle. it has not drained, rinse or spun. If I select the spin or drain program they work fine.

If I put the machine on a 90C water and leave for 10 mintues. 3 things tells the water is not heating. 1) if I drain the water out it is still cold. (2) I have an energy meter and this never goes up by the 2KW I expect. (3) the water in the drum is cold.

What I have done.
I order a new element. I noticed that the one of the power terminals had melted its plastic connector.
I have fitted the new element.
Repeating the 90c wash and it still does not heat.

Now reading about how to test an element with a ohm meter (on this website) I have done this.
The old one reads 25 Ohm and the new one now fitted is 25.5 Ohm.
Therefore I conclude the element WAS fine and new is ok also.

So, not the element. What can it be and how could I test it?

And what is a NTC that the post refers too?

many thanks

[electrofix]

Re: bosch 1200 classixx express not heating water

NTC is the electronic thermostat normally its in a hole in the heater

other fault it can be is a bad solder joint on the main circuit board. all heaters are switched by relays on the board and they dont always solder correctly and fail

Dave

[Pw98]

Re: bosch 1200 classixx express not heating water

thanks – I have measured the NTC and it has a resistance of 6.4 on a 200k scale. Is this ok?
I think I can see the relay on the circuit board, and have pushed all the connections hard. although none seemed loose.

[Martin]

bosch 1200 classixx express not heating water

The NTC is fine then @ 6.4 😀

[Pw98]

Re: bosch 1200 classixx express not heating water

thanks – any other clues? It is worth lifting up the machine, so I can access the conectors to the elements and fit a pair of crocodle clips to a voltmeter to see is power is getting to the element, or is it far to say that no power is getting there and the problem is elsewhere?
what are my next steps (apart from the high st for a new machine)

many thanks

[Martin]

Re: bosch 1200 classixx express not heating water

You mentioned the “power connector had melted the plastic” so have you ensured the heater connections are now good?

[Pw98]

Re: bosch 1200 classixx express not heating water

Ok. As best I could with the machine at 45 degrees and on a 90c program after filling with water, I assume it then heats the water, it reads zero on a multimeter. I have tested with an electrical screwdriver for any power at both element connections and it shows no power. The multimeter test I am not 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} sure the contacts were good 100 {e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of the time but the reading was always zero. I tested the electrical screwdriver in a wall socket and it works fine.

So there is no power to the element, which it pretty much a good conclusion as the element is brand new.

Where now ? Tracing the many brown cables to the circuit board is a bit of a hit and miss affair as there are about 6 that head that way.

Many thanks

[Pw98]

Re: bosch 1200 classixx express not heating water

Sorry yes the connections are now very good. The “melted” one I have cut the wire and replaced it with a brand new push on spade connector. If there is power in the cables then it will get to the element I am 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} sure.

[Martin]

Re: bosch 1200 classixx express not heating water

Time to look closely at the PCB, possible dry joint or faulty heater relay?

[Pw98]

Re: bosch 1200 classixx express not heating water

Thanks – I removed all the connections on the PCB one by one and and checked them and they all look clean and good. I replaced the heater element with the orginal one and it still (not surprisingly) not work.
This has a reading of 26 Ohms.

I see that one wire goes to some kind of device at the top of the machine, but held on the side of it. This has 4 wires to it. Its about size and shape of a fist The other wire goes to the main PCB. (Pressure switch??)

I cant see the heater relay on the PC (or is it that white square housing just behind the dial)? When the motor clicks in to turn the drum I think I can hear it click from hear. so I dont think this is it.

many thanks

[iceman201]

Re: bosch 1200 classixx express not heating water

Hi, sorry to bring up an old thread, but i have exactly the same problem except mine started after i did a 90c wash with soda crystals to clean the machine.

Now the water does not heat up, does not drain and refill during a cycle, it constantly stays on the wash cycle but timer counts down and when it reaches 0.01 on the timer it just continues washing forever. the water can be drained using the drain program.

I have cleaned the waste pipe and the filter on the bottom right which was full of limescale. i have also cleaned the pump as much as possible but still no difference. i can see the element is covered in limescale but havent managed to remove it to clean.

any ideas what the issue could be?

thanks

[Martin]

Re: bosch 1200 classixx express not heating water

Heater duff. 90 degs with a jacket of limescale blew the integral thermal fuse.

The trade is well aware that doing a 90 degs wash (a.k.a, a Service Wash) will most likely bugger the element under these conditions. It’s good for the sale of new heaters don’t you know. 😉

[iceman201]

Re: bosch 1200 classixx express not heating water

Is this a straightforward job to replace or do i need to get a local guy?

[iceman201]

Re: bosch 1200 classixx express not heating water

Also looks like their is not enough water filling on a normal wash

[Martin]

Re: bosch 1200 classixx express not heating water

iceman201 wrote:Is this a straightforward job to replace or do i need to get a local guy?

A simple enough job if you have the tools and have mechanical/electrical experience.

It is not and expensive option getting a local firm in either.

[Author]

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