What could be wrong with my dishwasher?

[Benjaminpalma]

Hi folks

My dishwasher is washing, but not heating the water or heating up to dry the dishes.

I've pulled the dishwasher out, but there doesn't appear to be any fuses or panels to check - just a lot of galvanised sheet steel...

It's an 'Ignis' but the handbook is lost and I don't even know what model it is to try to find one online.

Anyone know of anything obvious to check?

Thanks.

[NDA]

Sounds like the heating element has gone.

A new element is probably in the £30 range, but you'd obviously need to know the model number.

[singlecoil]

Do you have a meter? As NDA suggests, it's probably NFG. Put a meter across it and check, it it's open circuit, replace it, probably dozens of sellers on ebay can supply.

[Benjaminpalma]

Thanks, guys.

I took the bottom panel off... it all seems to make sense. The heating element is integral to the main water pump. There's continuity across the heating element ends, so that's fine. So it must have been a faulty connection somewhere... I'll just pop it all back together and see if it's now working...

[Sticks.]

Useful site if you need parts or advice http://www.espares.co.uk/

[Benjaminpalma]

Benjaminpalma said:

Thanks, guys.

I took the bottom panel off... it all seems to make sense. The heating element is integral to the main water pump. There's continuity across the heating element ends, so that's fine. So it must have been a faulty connection somewhere... I'll just pop it all back together and see if it's now working...

Hmmm... water still not heating. Must be the control board...?!

[jet_noise]

Dear Benjaminpalma,

there should be a rating plate/sticker somewhere on the machine which will give you model & serial no. If you can find it then have a websearch, there a fair few fora for white goods maintenance issues.

I fixed my Bosch machine with a similar fault. The most difficult part was working out how to get at the control board.
The fault was common at the time - cost cutting and lead free solder introduction, a poor soldered joint on a relay. It was easy to spot - bit of discolouration and an obviously "dry" joint. Bit of solder and Robert was a parental sibling,

regards,
Jet

[Benjaminpalma]

jet_noise said:

Dear Benjaminpalma,

there should be a rating plate/sticker somewhere on the machine which will give you model & serial no. If you can find it then have a websearch, there a fair few fora for white goods maintenance issues.

I fixed my Bosch machine with a similar fault. The most difficult part was working out how to get at the control board.
The fault was common at the time - cost cutting and lead free solder introduction, a poor soldered joint on a relay. It was easy to spot - bit of discolouration and an obviously "dry" joint. Bit of solder and Robert was a parental sibling,

regards,
Jet

Thanks, Jet.

I got to the control board, but didn't take it out as I wanted to see if I had already fixed it.

Who would have thought that they could make things with dry joints in this day and age!

I'll give it a whirl(pool)...

[Benjaminpalma]

I'm an idiot (I think!)...

I checked the control board circuitry - no dry solders.

Then I thought to recheck the heater terminals. With nothing attached to the terminals, there is no resistance whatsoever.

Surely there should be some resistance if it's going to get hot...?!

Can they break in such a way so as to leave the circuit 100% closed - as well as 100% open?

[singlecoil]

If it was short circuited I expect there would be fuses blown, components melted, trip tripped etc. Is the meter accurate and on a suitably low range?

[Benjaminpalma]

singlecoil said:

If it was short circuited I expect there would be fuses blown, components melted, trip tripped etc. Is the meter accurate and on a suitably low range?

Thanks. Yes - that's a good point. I can't see any fuses or circuit breakers, though.

I'm using an analogue multimeter. Resistance is shown on an exponential scale, so half the scale shows 0 - 5 ohms.

The element says it's 2040 watts / 240 volts.

If Watts / Volts = Amps and Ohms = Volts / Amps, then the resistance offered should be about 24 ohms, shouldn't it?

Awww... am confused now...!

[singlecoil]

Benjaminpalma said:

singlecoil said:

If it was short circuited I expect there would be fuses blown, components melted, trip tripped etc. Is the meter accurate and on a suitably low range?

Thanks. Yes - that's a good point. I can't see any fuses or circuit breakers, though.

I'm using an analogue multimeter. Resistance is shown on an exponential scale, so half the scale shows 0 - 5 ohms.

The element says it's 2040 watts / 240 volts.

If Watts / Volts = Amps and Ohms = Volts / Amps, then the resistance offered should be about 24 ohms, shouldn't it?

Awww... am confused now...!

If there weren't any protection circuits inside the dishwasher, then the breaker in your distribution board would have gone (or a fire would have started) assuming the heater is acutally short circuited. That does seem very unlikely, though. Is the meter a good one? Have you tried it across a kettle element, or something of that sort? Might be worth doing so as a comparison.

The next step, assuming the meter checks are inconclusive, is to see if you are getting any voltage across the heater when the machine is in operation, and having got to that part of the cycle where the heater should be on. Could be both tricky and dangerous to get access though, so that might not be a good idea depending on your knowledge and circumstances

[eastlmark]

you should read around 30-100ohms across the heater teminals with nothing connected. IE, with a normal meter it should read almost a short circuit but open circuit to earth.
If its the one combined with the wash pump (ie made within 2 years or so) then your are fecked as it is a very pricy part and does not come with the motor or the special clips to fit it.
Model number is on the side of the door, open it and look down the edges, you will see the rating plate there. If not then under the door opening about where your toes are if you stand in front, usually some stick on bar codes with the model number/service code underneath.
Its a crap heater, we get loads with the same problem, if its an intergrated appliance then it may be worth a repair, if its freestanding then forget it.

Edited by eastlmark on Saturday 16th April 20:39

[eastlmark]

singlecoil said:

If it was short circuited I expect there would be fuses blown, components melted, trip tripped etc. Is the meter accurate and on a suitably low range?

he doesnt mention short circuit, quite the opposite.

[singlecoil]

eastlmark said:

he doesnt mention short circuit, quite the opposite.

Actually he did.

Benjaminpalma said:

Then I thought to recheck the heater terminals. With nothing attached to the terminals, there is no resistance whatsoever.

[eastlmark]

singlecoil said:

Actually he did.

OK, you are pedanticly right but I think by "reading no resistance" he means open circuit. ie: no reading showing = a very high resistance.
It is impossible for these type mineral insulated heaters to go short circuit accross the terminals. Can short to earth only.

[singlecoil]

eastlmark said:

OK, you are pedanticly right but I think by "reading no resistance" he means open circuit. ie: no reading showing = a very high resistance.
It is impossible for these type mineral insulated heaters to go short circuit accross the terminals. Can short to earth only.

'Pedantically right', that's a good one, I must remember it.

[Benjaminpalma]

Thanks for help, folks!

Checking the heater element again, I think I may have been checking the wrong parts. Checking across the two spade terminals where the heater 'plugs in' to the rest of the dishwasher, it's an open circuit. I'd been checking what I thought were the two ends of the heating element as access to these were much easier.

A laughable schoolboy error I know, but you live and learn...

[eliot]

You should consider getting a digital meter - they are really cheap now.
http://cgi.ebay.co.uk/LCD-Digital-Multimeter-Voltm...

[Benjaminpalma]

eliot said:

You should consider getting a digital meter - they are really cheap now.
http://cgi.ebay.co.uk/LCD-Digital-Multimeter-Voltm...

I'm off down Maplin tomorrow!