Miele T294C Service Advice

[EWG]

It would appear that my machine may be failing due to a faulty NTC?
I have read a few previous threads on this but before setting out to explore possibilities would welcome some direction on best approach.
I have put the machine into service mode and based on my reading of the Drying light flashes it shows 4 long the 3 short before repeating. I have been unable to locate what this means from a general search. I am happy taking the machine apart and measuring NTC's etc.
The machine currently fails to operate for more than about 30 seconds regardless of cycle chosen, so the cold air one results in the same failure ie beeping and Cool Air light after 30 seconds.
Machine details are Type HT19-1
M-Nr 06985030
NR 55/090357462
It is almost 10 years old and until recently has worked without any trouble. I would love to get it working again so thought that asking about the error code would be a good first stage. As Miele parts are not cheap I would replace it with an alternative machine if advice here indicates that it is not repairable.
Thanks for any suggestions.

 

[sircerebus666]

As I say to everyone , have you emailed Miele (it is their machine after all) and asked them what the error code means?

Tumble dryers are simple beasts not much to go wrong with them and with yours it sounds like the heating element may have failed , do you own a multimeter to test it?

Also whilst you are at it test the resistance on the ntc

 

[EWG]

Thanks for replying.

I have emailed Miele as suggested ( I had visited their site previously but could not find any useful troubleshooting info).

Reading the previous posts on this site that reference this particular model (and especially zipper's) I have completed a number of multimeter based tests as follows:-
lid-off and measured temperature sensor (NTC) from connector at rear pcb, this gave 15.2 k ohm which is close to the ballpark 14.8 mentioned by zipper. Next checked at heater plug which gave about 92 ohm.
back-off and established continuity of thermostat.
front-off and measured NTC which showed 13.3 k ohm

I have also checked all filters and condenser unit which are clear of of debris.

I will update if I hear back from Miele.

 

[sircerebus666]

That resistance at the heater is too high , doesn't your heater have two coils? Have you tested both of them?

Have you also done a continuity test of your heater(s)?

 

[EWG]

Update on tests following your advice.
Please see attached diagram for reference. Measurements from connectors highlighted are as follows-
2/3 to 2/1 showed continuity and measured 24 ohms
2/2 to 2/1 showed no continuity and 69 ohms
2/2 to 2/3 showed no continuity and 100 ohms

You are correct about the two elements and your initial thought that it is a heater problem would seem to be confirmed?

Look forward to hearing your thoughts on these readings and thanks for the help with this.

 

[sircerebus666]

Your tests do confirm one of the coils is dead

That's probably the most expensive part too.....

 

[EWG]

Your expertise has been invaluable in identifying the problem. The outcome points to the end of this Miele.
The part on eSpares is around £250 and that is just not worth doing for a 10 year old machine.
The possibility of a future NTC or thermostat failure makes buying a new Bosch Series 4 a better prospect. Can't trust that Miele claim of '20 year lifespan' as this machine has had very limited use in a two person household.
I am very grateful for all your help so thanks again.

 

[EWG]

A brief update on the above.

First Miele replied but offered no help with the service code. They would arrange an engineer visit though but that would cost £££ plus parts which is not an economical solution. My email to Miele did allude to the 20 year lifespan expectation but that received no response. I conclude that offering a two year warranty on a 20 year lifecycle gives more than a hint about what to expect.

On a practical note I thought I would examine the heater box just to see what £250 would get me. It is a simple two part case of thinnish metal held together with 6 tabs. Loosening these gives access to the innards which are two sets of simple coiled heater wires. There is no extra expensive technology included. On Ebay I see other brand dryer heater assemblies available for less than a third of this. I looked again at the coils and can confirm that they are not made of pure silver nor is any part of the casework precious metal.

There was very little fluff on the coils which was easily remove with gentle compressed air. I then checked continuity and no surprise it was fine for the main, larger coil, but for the smaller secondary one it was erratic. This coil looked okay ie there was no obvious break and it was possible to continuity check each coiled row. I had hoped that this would reveal a break but oddly I kept getting good continuity on a row by row basis but when I measured across the entire coil element it was very hit or miss (mainly miss). I carefully reassembled and reinstalled. Re-measured all values and these were almost identical to those given above. Thus confirming the faulty heater conclusion.

Cleared the error code and ran a cool cycle and it worked without faulting. Ran a full Normal Plus cycle and that worked too with all items dried indicating that the main heater was effectively operational. Tried another load on Normal and that too dried okay.

This morning I tried a cool cycle and it reverted to error again. The machine had not been moved or powered off at the plug overnight so very puzzling. back in to service mode and error as before, cleared this and all working again.

I expect that in another 24 hours it will be back to error state!

Still looking for an alternative dryer and was not impressed to read just how poorly my first choice alternative, Bosch, were rated on Truspilot.

 

[sircerebus666]

If the continuity is erratic it would explain why it's only going into fault when it feels like it!