AEG Lavatherm 56600 / 91601409901- No heat?

[Big-Ashy]

I`ve had this tumble dryer for approx 10 years and it has worked faultlessly with regular maintenance. Unfortunately there is no heat being produced throughout any of the cycles, so as I have a good electrical background, I thought i`d have a go at finding out what was wrong and replace the faulty component.
At first, I thought it would be a simple control circuit issue, but the thermostat and the klixon on the heater element both have a circuit through them. I then checked the heater element and this has a live and neutral to it and there is resistance through the element, but no heat. There are five cables going to the heater element assembly, I presume it is a two stage heater, is it possible for these elements to have resistance and power to them and not work? Am I barking up the wrong tree or is it a simple case of replacing the heater element ❓
Any help or advice would be much appreciated, Adrian.

[Specialist01269]

Re: AEG Lavatherm 56600 / 91601409901- No heat?

2 Questions: What was the resistance across the Elements? What did you test the voltage with & was the Element connected when you tested?

PLEASE REMEMBER POWER OFF & PLUG OUT BEFORE TESTING.

[Big-Ashy]

Re: AEG Lavatherm 56600 / 91601409901- No heat?

Many thanks for your swift response!

Since your post, I have removed the heater assembly from the machine and opened up the galvanized casing to expose the elements etc.

I use a Fluke 110 Multimeter for testing and the 5 pin jack plug was disconnected throughout.

When the casing was opened up, it revealed that there were four elements in total stacked on top of each other and wired in series. The five cables wired to the assembly can be described as below:-
Brown/Blue – Phase and neutral wired to the either end of the four elements wired in series.
Grey/Black – Klixon coil circuit
White – Wired to the middle of the four elements to create a presumed star point affair?

Resistance measured as below:-
Brown/Blue – 82.9 Meg ohms
White/Blue – 46.3 Meg ohms
White/Brown – 37.3 Meg ohms

Whilst having the assembly in pieces, I also noticed that there are two small resistors in circuit. One is in the klixon coil circuit and one is wired in series with the white cable before it connects to the middle section of the four elements.

Both of these are open circuit and have no resistance at all when tested, could these be blown and at fault?

After this I reassembled the heater, I did a live test on the 5 pin jack plug. The black cable (coil circuit) had 240V on but was not present at the klixon due to the resistor which is open circuit. Could this be preventing the coil circuit being complete and energizing the relay back at the pcb to power the heater?

Apologies for rattling on a bit, but I have to do the same in my field of work and appreciate as much info as possible.

Many thanks, Adrian.

[Specialist01269]

Re: AEG Lavatherm 56600 / 91601409901- No heat?

Hiya: No your not prattling, that’s good info. you only gave readings for 3 elements, but going on your readings then the elements are open circuit.. as well, they should read in Ohms not Megohms. Can you check that for me again just to make sure you are definately across the ends of each element.
Just checked my manual for this machine & it only lists 2 Elements fitted, 1 x 1100 watt should be roughly 50 ohms & 1 x 1400 watts should be roughly 42 ohms.

By the way the Fluke 110 is an excellent meter, got one on my workbench. Hope you don’t mind me asking but what do you do ❓

Would be interested to know how you got the readings you gave on a Fluke 110 ? 😕 The resistance range only goes up to 40 Megohms.

Andy.

[Big-Ashy]

Re: AEG Lavatherm 56600 / 91601409901- No heat?

Hi Andy,

My apologies, those readings are in Ohms and not Megohms. 😯

Now you have said that there are only two elements, I now understand how they are wired. As mentioned previously, there are four elements stacked vertically and wired in series, but the white cable wired to the middle of the four is the common neutral to make the two wired in series either side to give the 1100 & 1400 Watt heaters.

Heater one – Brown & White – 38.2 Ohms.
Heater two – Blue & White – 46.4 Ohms.

From what you have mentioned above, these two resistance values don’t seem to far away and as I mentioned previously the neutral is wired through a small resistor which is open circuit and the coil circuit (Black & Grey) is also wired through a similar resistor which again is open circuit but with no obvious signs of “blown” damage. ❓

Are these resistors essential or can they be wired out of circuit. ❓

Hope this clarifies the situation, but please feel free to ask for any further information. 😀

FYI, I am a commercial refrigeration and A/C Service and Installation Engineer with 25 years experience, sound like a right old git now don’t I? 😆

[Specialist01269]

Re: AEG Lavatherm 56600 / 91601409901- No heat?

Us oldies need to stick together mate 😆 When you say resistors do they actually look like resistors or are they like a small stat i.e NTC type ?
If they are NTC type you should be able to get them, if like standard resistive elements then it’s probably time for a new element assembly.
The resistors are essential to correct operation.
Just for you to know this can be caused by opening the door mid cycle.

Firm I used to work for did all the wiring for commercial refridgeration systems for Tesco stores but I never got to do any other work on them.
I don’t repair refridgeration equipment as I can’t see the point spending on the kit for just 1 or 2 jobs. Thanks for clearing up the resistance readings for me, I was beginning to get worried about you 😆
Andy.

[Big-Ashy]

Re: AEG Lavatherm 56600 / 91601409901- No heat?

😯 Yer, big initial outlay of test equipment and specialist tools in my game, but been doing it that long now, I don`t even think about the cost over the years 😆

These are defo resisitors and not the NTC type you refer to, but are that small and thin in diameter (approx 20mm long and 4mm diameter) I can`t make out the resistance marked on them in Ohms.

Both resistors are defo open circuit, I`ll give Serviceforce a bell in the morn for a price on a new heater assembly, unless you can recommend another supplier elsewhere. ❓

Many thanks for your advice and asistance Andy.

Cheers,

Adrian. 😀

[Martin114]

Re: AEG Lavatherm 56600 / 91601409901- No heat?

Hi Adrian, I think the resistors you mention are in fact microtemp thermal fuses.

[Big-Ashy]

Re: AEG Lavatherm 56600 / 91601409901- No heat?

Martin114 wrote:Hi Adrian, I think the resistors you mention are in fact microtemp thermal fuses.

😀 Thanks Martin. I am not familiar with this type of fuse and they look very much like a resistor but are open circuit with no evidence of heat damage or blow marks.
Adrian 😀

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