Whirlpool L1373 - damage possibly done by a centipede

[Yavorescu]

I found this forum via Google and this excellent thread. I have a washing machine Whirlpool AWE 6516 that started throwing F23 error. If set on normal washing program It takes some water, spins a few times and in about 10s the error is displayed. The same happens if I run the test program.

What I've tried so far:

1. I checked the hose of the pressostat and the pressostat itself - it clicks when the machine takes water and the contacts appear to be working.
2. For extra safety, I replaced the pressostat with a new one.
3. I checked the cables and connections between the pressostat and the main board (L1373).
4. I checked all three relays on the board by powering them with 9V DC and measuring the contacts.
5. As advised on another forum, I checked the 470kΩ resistors immediately after the pressostat.
6. Heater is OK, no leakage.
7. I replaced the heater with a lamp; same behavior (the lamp doesn't lit up but that's probably because the error is thrown before the heater is powered).
8. I changed the polarity of the power supply.
9. The drain pump is working.

When I disassembled the machine I noticed a dead centipede on the back of the main board. Is it possible to cause damage to the board? There are no obviously burnt elements. Any ideas how to proceed further? I attach a photo of the centipede.

 

[shrtrnd]

I'd de-bug your board, then make a pretty good bet that the centipede shorted some of your components.

 

[Yavorescu]

Of course I removed the bug. The board seems to behave properly in general, e.g. if I disconnect the NTC sensor or the heater, I get the respective errors. How to find out which component(s) are for replacement?

 

[shrtrnd]

You'd have to find somebody with a schematic to point you in the right direction.
I'd start with that 8-Pin IC near the tail of the centipede that looks to have taken a hit.
You don't have a problem with your washing machine, you have a problem with the control board, and nobody
can tell from looking at it what circuit is damaged. You need a schematic and a voltmeter to trace the problem.
In a case like this, unless you have the troubleshooting knowledge needed and the schematic, I'd be looking for a replacement board, or some place that offers a trade-in allowance for one.
You have damage caused by a specific short to some component(s). This is a unique-case failure that you're
not going to find an already-or-similarily encountered remedy for. Did you track down the 'F23" Error code, to at least identify which section of the control board you have the problem with?

 

[Yavorescu]

I have found one schematic, although I admit I'm not certain whether it is for my board ("domino" is slightly confusing).

The IC at the tail of the centipede looks like U001 on the diagram and it seems unrelated to the pressostat circuit. Perhaps I should check the SOT23 diodes (BAV99) first in the pressostat circuit on the left?

I've read almost anything I could find about "Error F23" code. It is an obscure problem that may occur due to heater leakage, drain pump, poor connections or some other kind of fault. In most cases replacing the heater is the solution. However, I'm 100% sure my heater is fine. Some people have experienced this, changed everything (heater, pump, NTC, board) and the problem remained. The board is fairly expensive, it's not worth replacing it and I'm not sure it'll help.

 

[Tha fios agaibh]

Google told me F24 error means it's not coming up to temperature.
Try looking for the components upstream of the heater connections, such as a relay or triac. I'd guess it's either not passing power to the heater, or a thermostat circuit is open somewhere.

 

[Yavorescu]

The error code is F23, pressure switch failure.

 

[shrtrnd]

That doesn't necessarily MEAN the pressure switch failed. It just means your control board is convinced the pressure switch failed. I'd be believing the control board is generating erroneous signals because of circuit damage from the bug. The board is probably convinced something failed that didn't, and is generating the signal to shut-down washing machine operation as the result.
I know new parts are expensive and I don't know what kind of access you have to after-market or used parts.
Did you try Googling the part number for the board and see what comes-up.
Where I'm at, I have vendors for new parts, vendors who repair boards, and other vendors who sell used parts from scraped machines. It's almost impossible to troubleshoot that board yourself without a schematic.

 

[Tha fios agaibh]

Sorry, F23: An appliance forum says:
Wash level switch and level heater safety switch are on at same time.

Perhaps try resetting fault and try running it again but disconnect one of the switches and see if it still gives the f23 fault.

 

[Yavorescu]

Yes, that's exactly error F23. There are two contacts, one normally opened and one normally closed.

I don't know how to reset the board except running the test program. If I disconnect one of the switches, I still get the same behavior. If I disconnect the other one, the machine constantly fills with water; I have to terminate the program or power it off.

@shrtrnd: There are no vendors who will attempt to repair the board here. From time to time people sell parts, usually from their own machines. A month ago there was a sale announcement for this board, but it's no longer active. There are two numbers on the back of the plastic case containing the board: 461975306611 and 461971402174.

 

[shrtrnd]

Sorry for your situation/ lack of spares or support.
If I were you, I'd contact Whirlpool directly via email and explain your situation. Depending on if you get a paper-pusher or somebody who actually cares, the main office may be able to direct you to help.
Most companies know their brand is important, and having somebody left out in the cold with one of their machines is not good business and bad for their reputation.
Good luck with solving this.

 

[Yavorescu]

There is an official Whirlpool service in my city, but they can only sell a new board (and replace it, which I can do myself). The machine is 10 years old and the price of a new board is approximately half the price of a new machine.

I'd buy a used board if the price is reasonable and it's 100% certain that the board is defective. I was hoping that with some expert guidance I could figure out which elements to replace. I'll try to find out if the board (at least the circuit related to the pressostat) corresponds to the schematic I've posted.

 

[Tha fios agaibh]

if I disconnect one of the switches I get the same behavior. if I disconnect the other one, the machine constantly fills with water

That tells me the problem is with the first switch or the logic section related to it on the board.

 

[Yavorescu]

I guy from the official Whirlpool service agreed to take the board for diagnostics. He said there's nothing wrong with it -- no shorted elements, all circuits appear to be working, final diagnostics with their aparatus/program went OK. He told me there were numerous accumulated errors (most probably because of the multiple tests I've made) and that could be confusing the logic of the board so he reprogrammed the EEPROM. His advice is to refrain from buying a new board because in his opinion there's no damage.

Unfortunately after his intervention I get the same behavior (error F23). I'm out of ideas.

 

[Tha fios agaibh]

There's a chance your not looking at the correct switch. You need to find the "Level heater safety switch" (whatever that is) and verify it changes state. You've been looking at the pressostat but I'd guess that's not it.

Btw, in the future can you please post pictures instead of pdf files?
I'm not a fan of downloading files.

 

[Yavorescu]

I couldn't find an image version of the schematic, sorry.

The pressostat has two switches (or two pairs of contacts, like a typical relay) -- one is the level heater safety switch, which ensures there is enough water in the machine before engaging the heater, the other is for the water level and controls the water intake. They are triggered at the same time. It is expected if one is switched and reports sufficient water level, the other to be on as well to indicate it is safe to power the heater. Mismatch is abnormal situation, hence the fault.

 

[Tha fios agaibh]

Doesn't make much sense. You say the board has been ruled out, and the pressostat which contains the switches has been replaced.
What else could it be, a short in the wiring from the heat level safety switch? Not very likely.
I would go back to the pressostat and check the normally open contact (with water low) (should be heat level safety switch) and verify it is changing state with a meter set to ohms or continuity and check at different water levels.
You know the other switch is fine because the water shuts off when it should.
How many wires go to the pressostat?

Could it be something like the hose going to pressostat having restrictions?

 

[Yavorescu]

There are 4 wires to the pressostat. I have already measured them with a multimeter as connected to the board. The contacts change state simultaneously -- the normally opened becomes closed and vice versa. The hose is clean and the pressostat is actually triggered when the water level is high.

I spoke with the technician again and asked him if he can rule out a problem in the pressostat circuits on the board. He said they cannot guarantee that with 100% certainty as they cannot simulate the external stuff (heater, pressostat, drain pump, motor, NTC, valves, etc). They need the whole machine to perform full tests but are reluctant to do it.

 

[Tha fios agaibh]

The contacts change state simultaneously -- the normally opened becomes closed and vice versa. The hose is clean and the pressostat is actually triggered when the water level is high.

Then, why does the print say there's level 0, and level 1? It says pressostat level 1 (one switch) which has test points to verify signal on the board which ends on pin 26 of U005.

Level0 is from (without p) "ressostat" that ends on pin 9.

I don't know what switch is what, or if the drawing is accurate. I do think it's likely a board problem but I wouldn't expect expert board diagnostics for the appliance tech.

 

[Yavorescu]

It's a 1-level pressure switch (part No.461971090502).
I suspect the schematic is not exactly for my board (there's no "Domino" written anywhere on mine).