NEFF Dishwasher not heating water

[JamesHughes]

My Neff dishwasher has just started showing the same symptoms - the water isn't being heated, and the program seems to run for ever.

I have checked the resistance of the heater, and is 23ohms so that seems OK.

Not sure how to check the thermistor though - does anyone know if its the device on the top of the instantaneous heater with two plugs? I have measured across both plugs at this point and both are open circuit.

Not sure what to do here. Normally I try to fix stuff myself, but this looks like a horrible job - no access at all - was a pain even getting the readings I have.

Should I just replace the washer at £500 or so (its > 5 years old) or get someone in to fix it (£200?)

James

 

[zipper]

The device on top of the instantaneous water heater is a combined NTC/temperature safety switch. Neither should read open circuit. The NTC should measure around 48k ohm at 25C (dropping to around 9k ohm at 65C). The temperature safety switch opens at 85C. These devices cost around £25 & are relatively easy to change. If you require further information post the machine E-number engraved on the door lip.

 

[JamesHughes]

Thanks Zipper,

S5453X1GB/56, Neff built in dishwasher. Looks like a sod to remove/replace - couldn't even get the cover off when I was prodding about.

As an aside, first time I've been accused of a post hijack. Odd since I'm still of the opinion that my problem exactly mirrored that of the original post!

Oh well. Perhaps the thread was too old.

James

 

[zipper]

Always better to start a new thread rather than tag onto an old one. They often get ignored....too much heavy reading wading through a dozen posts to get the gist of the thread.

Some of these Neff models have a removable baseplate, unfortunately I don't think yours does. So to get at the combi NTC you would have to remove the side panels & the front cover below the door. Lie the DW on its back. There are 4 screws holding the stainless steel tank to the plastic base (one at each corner. Remove the front two & the right hand side rear screw. Loosen the last one but don't take it out. You ought to be able to lever the tank away from the baseplate enough to remove the NTC (bayonet fastened). You only need to gain a few centimetres of room to get it out. Wedge a piece of wood between the tank & baseplate at the back to keep it open while you work in there. You can test the NTC better when removed.
It isn't as bad as it sounds

 

[JamesHughes]

Glad it isn't as bad as it sounds! 'Cos it sounds pretty bad!

Real shame that modern appliances are so difficult to fix. Deliberately so I guess - they want you to buy new all the time.

Anyway, I'll grab a new switch and swap them over. Apart from a problem on the circuit board (and all the lights and buttons seem to be working OK), this seems the only thing that could be going wrong.

Thanks for the help.

James

 

[JamesHughes]

Finally got round to replacing the sensor, but sadly this has not fixed the problem - the water still isn't getting hot.

Replacement wasn't as bad as its sounded - probably didn't need to undo the 4 screws holding on the base - there was enough room to wiggle the sensor out.

Not sure what the problem might be now - the heating element itself is returning the right resistance, so that seems OK.

So now I have a dishwasher full of cold water that needs draining. Does this require sponge work, or can I get the washer to drain itself somehow?

James

 

[zipper]

Sorry it didn't solve your problem James
To empty the machine start any program & it should pump out, or use the reset buttons while a program is active. Alternatively lower the drain hose to floor level & drain it into a bucket/bowl etc. There are only so many possible causes of no-heat problems: Element, wiring, pcb, NTC/thermostat, under-filling, pressure switch...think that just about covers most things. There is a safety pressure switch on the end of the instantaneous water heater, if the machine under-fills this may not activate, you can check it with a multimeter. If it doesn't activate try filling a little more water by hand. Take off the door skin & side panels. Look for blockages in the matrix & transfer hose. Check the wiring for breaks (especially at the flex point at the bottom of the door). Then inspect the pcb for blown components/tracks. Looks like you've got enough to keep you busy for a day or two. Good luck

 

[Leccy758]

Not seeing the original post that was threadjacked ? so here goes.

Most of the heater failures I see on BSH (Bosch, Siemans, HSF 'Neff is part of this group') dishwahsers is down to a blown solder joint on the PCB (Normally on the neutral on the heater relay) or the Heater relay itself failing.

Have you checked the PCB at all. Do you have 240V across the heater when the appliance is running (On the heater plug). Most of these actually switch the neutral so you can have 240 volt between both sides of the heater element and earth or the chassis.

 

[JamesHughes]

Thanks for all the help guys.

I tried to run a program to empty, and also reset during run, but neither seemed to empty the washer - perhaps because the water isn't getting hot and it never manages to finish the program. I'll try the bucket approach.

Where about is the PCB to which you refer? In the door? Happy to resolder, if I can find it!

I'll check to see if I have 240v across the element. Have a DVM, but I'm used to lower voltages than 240 (cars are 12v!) - where should I measure between?

One things I haven't figured out yet - this is a built in washer, and there is a wood front attached to the door - how are these normally attached (and therefore removed!)

James

 

[zipper]

Here are a set of constructional drawings for your machine (there are several pages). Follow the points mentioned in my last post...its a matter of elimination. Seems like you may also have a drain issue on top of everything else. Here's hoping for a quick fix...but you may find a wonky pcb is at the root of your troubles.
http://www.neff-eshop.com/eshop/neff/gb/prodp.htm?prod=S5453X1GB/56&ESHOPTYPE=A (click on the part numbers for a description).

 

[Grateful1]

Not seeing the original post that was threadjacked ? so here goes.

Most of the heater failures I see on BSH (Bosch, Siemans, HSF 'Neff is part of this group') dishwahsers is down to a blown solder joint on the PCB (Normally on the neutral on the heater relay) or the Heater relay itself failing.

Have you checked the PCB at all. Do you have 240V across the heater when the appliance is running (On the heater plug). Most of these actually switch the neutral so you can have 240 volt between both sides of the heater element and earth or the chassis.

Thanks Leccy758
Had the no heat problem stripped machine down thinking was the element
all checked out ok then saw comment above and tried PCB and 1 blown joint on the neg side heater relay, resoldered now works fine
just thought i'd post so others can try this first
Thanks again
yes i know its an old post but might help others