Miele T4659Ci

[DJB2]

Purchased second hand tumble dryer off Ebay over a year ago - paid only £150 for what looked like a fairly new dryer. When it works, it's great but unfortunately it has been plagued with 2 problems. The first one is now fixed - the display would indicate that water reservoir was full despite the outlet pipe being connected directly to a drain. Turned out that the water pump which turns on and off periodically required lubrication. A small amount of 3 in one around the moving parts and I've never had this error message since (about 9 months).

Current problem is more challenging. I think that it is an overheating issue. Several things happen. Firstly the machine starts to groan once it's been running for a while. It's as if the motor is struggling to turn the drum. I think that this is due to thermal expansion. Next problem is regular non-specific error message (Technical Fault - call service, etc) and machine stops. Never gives more specific info such as error code. Most recent problem is TOC (thermal overload) has tripped twice. Fortunately, bashing on the ground trick has worked both times.

I've been reading other threads about Miele tumble dryer and it seems that it may be the rear NTC. In my machine, both produce a falling Ohms reading on heating but the rear one only goes down to 15 kOhms despite being immersed in boiling water. Front NTC gives appropriate readings (according to 'zipper') which is 15k at room temp to 1.5k at 85 C.

Just want to confirm that these NTCs which look very different (they are definitely both NTCs for sure) should give similar Ohms readings. If so I'll get a loan and buy a new one.

D.

 

[zipper]

No they are not the same & don't have the same base readings. The rear NTC should read approx 125kΩ at 20C. It would drop to around 15kΩ if heated to 75C.
The chances are the NTC is ok & the problem lies elsewhere...maybe a mechanical issue.

 

[DJB2]

Thanks zipper, just the information I needed. Sounds like from what you've said that both NTCs are ok although I'll need to check the rear one again with the figures you've provided.

Any other suggestions?

I have cleared out all the airways and the filters.

Groaning noise only occurs after it's been running for a while (and is maybe too hot) especially if it's run successive loads back to back. Is it possible to reveal error codes since I always only get 'Technical fault, etc ' message?

Thanks again.

D.

 

[zipper]

Cancel any program & switch off. Press and hold the start/stop button. Switch on the machine. As soon as the start/stop LED flashes, release the start/stop button. Immediately press and release the start/stop button 3 times and at the 3rd time hold it pressed in until the service functions are shown in the display. Post any displayed error code or press the -/+ button to shuttle through codes stored in the error log.

 

[DJB2]

Tried this before after seeing your previous threads and couldn't get it to work until now. Looks like there are 3 fault codes:

F2
Heater bank NTC fault

F55
Max running time

F66
Air throughput fault

There's a down arrow with last message but pressing + button doesn't reveal any more errors.

What now?

D.

 

[zipper]

Which was the first error code in the log...F2?
F55 is a time override error (180mins exceeded) & only happens on residual moisture programs. Although this isn’t necessarily a fault as it can happen if the laundry is too wet or the drum is overloaded. If you have electrically conductive items repeatedly in contact with the drum (metal zips etc) it can also timeout in the same fashion. F55 can also be caused by a blocked air-path or heater fault, but as yours does heat you can rule out a heater issue. F66 indicates insufficient air-flow or air leakage. Usually this turns out to be a blocked air path but it can also be a motor or drum drive issue. F2 indicates a shorted or open rear NTC. However it can be caused by a faulty heater-bank if the element is dual circuit.
Check the following: Is the condenser blocked. Are the two removable filters in the door opening clogged (if they appear white remove them & wash well with fairy liquid/hot water). If the above is ok I suspect there a mechanical problem especially since you mention the motor seems to be struggling & you hear creaking noises.

 

[DJB2]

Thanks zipper.

Have cleaned out filters and condensor many times (including cleaning filters with washing up liquid). It seems to help a bit and Technical fault alarm goes off less frequently. I very much get the impression that when the machine first starts and for the next 30-40 minutes or so it works well and sounds fine. It's only once it's been running for a while that it starts to groan. The other thing that I've noticed is that when it reverses, the groaning noise stops for a while.

One other thing, plug doesn't reach power point so dryer is plugged into extension along with machine machine. Have noticed that extension plug (ie one connected to mains socket) feels quite warm so extension may not be up to the job. Not sure if this is relevant but I recall other thread mentioning similar issue.

D.

 

[zipper]

Run it on a timed cycle & see how that works out. Running multiple appliances on the same circuit (especially using extension cables) isn't ideal. The dryer alone will pull at least 2.5kW (around 10A). It is worth noting that the motor on this model was retrofitted with a 9uf capacitor, the original was 8uf. I still think you may have a mechanical issue, the only way to find out it to strip it down & check.

 

[DJB2]

Most of the time it completes a full timed cycle without event. Have managed to plug it in without extension - will see if that makes any difference.

What's the significance of motor capacitor rating?

If I stripped it down, what should I look for?

D.

 

[zipper]

The capacitor change is a Meile retro-fix. If when stripping down the motor is found to have an 8uf cap they recommend switching it with a 9uf. No reason given but most likely it improves motor function on heavier loads. The dryer spends most of its time only going in one direction, it has to be that way. Occasionally a random generator triggers a short reversal, this is to prevent the clothes from tangling. Does the drum turn easily by hand in both directions??? If you decide to strip it down I would do give it a good clean. Then check front and rear felt seals are seated properly, the drum bearing shells are fitted correctly and snapped into position, adjust the front roller bearings (if necessary), & check the intermediate drive belts for damage.

 

[DJB2]

Thanks zipper, will take it all apart when I get time.

I did look at the rear bearing before and apart from looking a bit dry, it seemed ok. I took the opportunity to fill the bearing shell with copper grease at the time. Didn't see the rear felt seal but front one looked ok and in the right position. I didn't take the drum belt off (wasn't sure how easy it would be to put back on).

The drum does turn easily in both directions.

What would cause the overheating (TOC has tripped twice)?

D.

 

[DJB2]

I ran a time warm cycle to try to identify where the groaning noise comes from. After 10-15 mins, the groaning noise was very obvious and the drum was so hot that I could not touch it. Hand rotation is now much more difficult. I then changed to cool timed cycle. After a short time (ie cooled down), groaning noise completely gone.

I'm sure that the groaning noise is caused by hot drum expanding and therefore becoming tight as it rotates. Does this sound reasonable?

Still not sure why it's overheating though.

I've also noticed that the fan seems to run at two speeds. Slow speed (would hardly blow out a candle) for most of the time and high speed (like a hairdryer rate of air flow) other times. I get the impression that the groaning noise (and overheating) occurs at times when fan speed is slow. Not sure why the fan speed changes.

D.

D.

 

[zipper]

The only option you have is to strip it down & find out what the problem is.
The motor is NOT two-speed...something is preventing it from turning freely.

 

[DJB2]

Sorry to labour the point but the process of changing from one fan speed to another would appear to be part of a normal cycle. It's as if it's switching from one mode to another (?part of the drum reversal process). I presume that the drum and fan are both run off the same motor so whatever speed the drum rotates at will determine the fan speed? I would also presume that when the drum rotates in the opposite direction, does this not mean that the fan also turns in the opposite direction?

D.

 

[DJB2]

I've managed to work out why the fan runs at two speeds. When the drum turns anticlockwise (majority of the time), the fan run at the lower speed. When the drum reverses and runs clockwise there seems to be a different gearing which must stop the fan turning backwards (and sucking air) but actually seems to double its speed. This clockwise, reverse action seems to only last for a few minutes before reverting back to the normal anticlockwise function.