I'm trying to solve a problem with my Kenmore Elite HE5t washing machine (model number 110.47091602). I believe this model is essentially identical to a line of washers under the Whirlpool Duet brand.
For most medium to large load sizes, the machine stops some time during/after the initial fill sequence and shows an F20 error code on the LCD display. This usually indicates insufficient inlet water pressure. Based on my web searches, it is most often caused by clogged inlet feeds, or bad inlet valves. It's also sometimes caused by a siphon effect on the drain hose causing water to drain as the machine fills.
The problem is intermittent in that some loads will go through just fine but the vast majority of loads end up stopping early with this error. However, so far, 100% of the time when the F20 error occurs, all we have to do is restart the cycle and it works fine the second time.
I'm fairly certain that the inlet pressure and/or blockages are not the issue for me. I've also replaced the inlet flow meter but that has not fixed the problem. I'm also doubtful that the drain hose siphon effect is the problem in my case but I'm running some tests now where I've moved the drain hose to drain directly into my laundry tub rather than the normal drain pipe. This will allow me to measure how much water is getting into the machine during the fill sequence and should also rule out the siphon effect as a source of the problem.
I've also ordered a replacement water level switch in case the one I have is no longer reliable. Again, I'm skeptical on this for a couple of reasons:
If the water level switch has failed then I would expect the machine to never work. But it does work intermittently. For example, I've put in a load of rags just now as a test load and sure enough, it's working.
I've taken the water level switch out and I've tried blowing into the inlet and I can hear the switch relays activating when I blow in and also when I let it exhale. I found a diagram online of the electrical terminal mapping and tried testing for continuity across terminals as I blew in and exhaled. My results didn't match what I expected from the diagram but I'm not sure how reliable the diagram was.
Here's my running theory: I'm thinking that the water meter switch has not failed entirely but is perhaps more resistant than it used to be (i.e. it takes more pressure to depress the manifold now than before), and that larger loads absorb more water in the clothes than small loads do. There's probably a timer in the onboard computer that limits how long the washer will wait for the fill level to be achieved and the above effects are combining to result in the error being thrown.
Does this make sense based on your experience? If so, is there not a way to adjust the sensitivity of the water level switch? I see what looks like several tuning screws on the back on the switch but I can't find any documentation anywhere on the web about the device so I have nothing to go by.
Any advice on where to look next is greatly appreciated.