Detergent Dispenser - ELTEK 100418

[stenzer]

Hi,

since a couple of days the detergent dispenser of my AEG (Typ: GHE423CA1; PCN: 91107602801) dishwasher does not work any more. To be more specific, the tab compartment does not open anymore during the washing process (opens when the front-door is opened, after the program ends).

I removed the detergent dispenser to have a closer look what may have failed. The first suspect is the linear-actuaror/thermalactuator [1, 2] shown in the picture below. The thermalactuator has the number 100331 40K T105 designed for 110/240 V 50/60 Hz and is manufactured by Eltek (like the whole detergent dispenser). For me it looks like the actuator should push against the lever when it is excitated. By moving the"white" lever in the lower left by hand, opens the tab compartment.

My question is, how to properly test the actuator as I never came across such a device. According to the datasheet it looks like it should be fine to just apply the nominal voltage (230 V_AC) for about/maximum 2 minutes (standard cycle with 2 min. ON – 5 min. OFF mentioned in section 6.7) and having a look if the piston moves.

Has anyone experince with these thermalactuators? Why are they used in such kind of application?

[1] https://www.eltekgroup.com/portfolio/linear-actuator/
[2] https://www.ontrium.com/get.aspx?id=191774

BR

--- Updated Jun 13, 2022 ---

... the electrical resistance determined with a DMM is about 2200 Ohm.

 

[BradtheRad]

For the remaining life of the appliance, the easy solution for you is to toss in a handful of detergent as you start a load. Or a helping of liquid stuff.

It's next to impossible for a home handyman to check for proper workings inside a dishwasher during a cycle.
Even if you order a replacement actuator (probably costing an arm and a leg), and even if they ship the right one...
the problem may instead be in the timing switch, or circuit board, or thermal sensor.

I imagine the thermal aspect waits until the water is hot enough to dissolve powder, so the timer pops the door open. If you see leftover powder after a cycle it suggests cool water or low water level or weak spray.

 

[stenzer]

Hi BradtheRad,

the tab is somehow slightly desolved. I will have a closer look on the mid-layer nozzles/sprinkler if they are blocked. The dishes are in general quite hot at the end of the program.

BR

 

[BradtheRad]

the tab is somehow slightly desolved.

Most likely inside the actuator is a solenoid. In time harsh soapy solution is liable to seep past the tab into the housing.
I was ready to suggest corrosion ate away a wire to the tab, breaking the connection. However you report electrical continuity.

An alternate theory is that built-up residue (or gradual heat expansion, etc.) interferes with the mechanism. So if you can figure out how to open up the actuator you might discover the problem is fixable. Be alert to springy parts jumping out as you separate the housing.

 

[stenzer]

Hi,

In time harsh soapy solution is liable to seep past the tab into the housing.

the actuator looks completely clean. Also I couldn't spot any contamination/leakage in the visinity of the detergent dispenser's backside.

So if you can figure out how to open up the actuator you might discover the problem is fixable. Be alert to springy parts jumping out as you separate the housing.

The actuator seems to be well closed, so it migth be quite challenging to open the housing, and even more challenging to but everything together, keeping everthing in place especially the counter-spring.

I have found suitable replacement actuators for about 10 - 15 €. So I would like to test my actuator first. Can I safely supply the actuator with 230 V, to check if the piston moves at al (as suggusted/asked in the opening post)?

BR

 

[BradtheRad]

The tabs plug into a connector, and maybe corrosion got into the metal contacts?

Ohmic resistance 2200 ohms makes 1/10 Ampere at 220 VAC. Or 22 Watts. Enough to get hot.
Rather than send full house voltage through the actuator, connect an incandescent lamp in series. 40 or 60 or 100 Watt bulb.
See if it's sufficient to activate the plunger. I suppose it pulls in?... Make and break contact to see if it moves freely.

 

[stenzer]

Hi,

it seems the whole issue has been caused by a large jar which blocked the tab-lid. Unfortunately the jar has a size which is just high enough to block the lid. Thus I wasn't able to spot this issue initially. Further I was to lazy to empty the dishwasher and doing the dishes by hand (lazy engineer ). Thus I tried the same unvaforable constellation about 5 times. I would highly recommend to make a test run with an empty dishwasher, if anyone has similar problems in future.

Regarding the thermoactuator, it seems they are also called wax-motors. A websearch for wax-motor delivers more search results e.g. [1].

Here are also pictures of the actuator's piston and lever position, which might be of use for someon in future.

[1]

@BradtheRad thank you for your suopport!

BR