The infamous F35 and SUD error code combo is one of the more common and confusing errors in Whirlpool-built Duet washer (also sold under the Kenmore label). The tech sheet is misleading and no help on this issue and has confused many a fine appliantologist locked in combat with this beast:
Analog Pressure Sensor Failure
If this failure is displayed, there is any malfunction of the steamer component detected by the Steamer Electronic Board.
1. Check if pressure hose is fixed correctly
2. Check if air trap is not blocked
3. Check if hose not blocked
Here's a typical tech sheet for these machines: http://appliantology.org/files/file/842-whirlpool-washer-wfw9500t-tech-bundle/
Brother Willie shines the light of wisdom on what's really going on with the infamous F35-SUD combo:
Don't get side tracked with the main control unit. A F35 error is almost always the Analog Pressure Sensor.
Unplugging the pressure hose and it still not working doesn't by no means mean the problem is the CCU. If you just remove the pressure hose and it works that would till you that it had something to do with a blockage in the air dome or pressure hose.
The problem is something goes wrong in the APS and it constantly thinks there is a SUDS issue.
DO NOT blow into the APS, the pressure transducer is a somewhat delicate electronic pressure sensor that is only designed for very low pressures and if it isn't already bad blowing into very well could damage it.
Here's the correct manufactures part#W10415587 and RepairClinic link:
A couple of years ago it seems there was a period that these were on backorder every where because of some manufacture problem and I'm wondering if maybe it was with the original manufacture for the pressure transducer because when looking up the numbers on the pressure transducer I couldn't find anything with the original manufacture number and seems now the only company making a lot of these pressure transducers is a company named FreeScale.
The original pressure transducer had what I think is a manufacture symbol of "EN" then
SPV5004G and a date code of K0?22 - the ? is a number that got scratched off when I pulled the computer chip board out of the plastic housing.
Here's the link to the pressure transducer on these APS If anyone is interested in learning a little about these units.
There are a bunch of surface mount resistors, a few triacs/transistors and capacitors then two other main larger IC chips, one being an actual micro-controller processor that takes the analog voltage signal that the pressure transducer outputs and turns it into a digital signal and communicates with the main CCU so it can detect very small changes in water level as a digital number that the computer can work with. The other larger IC chip I haven't been able to track down what it is yet, couldn't find any kind of reference to it, markings look like this:
A large "F" in leaning script which is a manufactures symbol then after that VG3AB
358 or (Maybe 368)
The micro-controller processor is made by ATMEL,
The pressure transducer on the small board should be somewhat simple to check if it is working since it is a somewhat simple pin out on the chip, it has eight legs coming out of the chip but only three of them actually have any function the rest are only board mounting points. Pin out 1 - is the corner that is notched and the pin has a small notch in it.
Pin 1 - Not used
Pin 2 - Vs - Supply Voltage (normally 5 vDC, max of 5.25 vDC)
Pin 3 - Grn - Ground
Pin 4 - Vout - Signal voltage output depending on pressure (1.0-5.0 vDc with a 5 vDC input)
My suspicion from the research I've done on these is the pressure transducer fails and the base out put voltage that should probably be right around 1.0 vDC with no water/ no pressure on the transducer shifts so it always sees SUDS.
The sequence of event you see when you get a SUDS error is for the unit to fill with something like 4 liters of water then sit for 4 or 5 minutes, (I forget - but on the SUDS error on the tech sheet it tell you this), to try and kill the SUDS then it drains and if it still sees the SUDS it goes to the F35 hard fail and locks up and sometimes only way to reset is to unplug machine to reset to unlock door.
There are two different part numbers for the APS and I believe they can be interchanged but you may have to cut one of the keys off the wire connector that plugs into the APS if you don't get the correct one. A while back when they were all on back order that was what people where having to do. The other APS can be found quite a lot cheaper than this one but I haven't determined for sure if they are interchange yet or not, they all use the same pressure transducer put the micro-processor actually has, I believe, an eprom memory and is actually programmed with assembly or c coding and it maybe different - possibly different size tubs or something to do with the one for the steamer or non-steamer models. So far the only two I've had to replace have been on steamer models so I don't know if they use the APS on non-steamer models.
Source: Kenmore FL Washer 110.46757801