This problem is a good illustration of how there’s just no substitute for actual hand-to-hand combat with broken appliances. Here’s an excerpt from the service manual on this fault code:
EXPLANATION AND RECOMMENDED PROCEDURE
F21 LONG DRAIN
If the drain time exceeds 8 minutes the water valves turn off.
NOTES:After 4 minutes the “Sd” error will be displayed, then
4 minutes later the “F/21” error code will be displayed. Press
PAUSE/CANCEL two times to clear the display.
1. Check the drain hose and make sure it is not plugged or
2. Unplug washer or disconnect power.
3. Check the electrical connections at the pump and make sure
the pump is running.
4. Check the drain pump filter for foreign objects.
5. Plug in washer or reconnect power.
6. If the above does not correct the problem, go to step 7.
7. Unplug washer or disconnect power.
8. Replace the pump.
I’ve worked on dozens of these washers and have only found the above service manual solution to apply once or twice. The vast majority of the time, I’d arrive and all the washer would do is drain and flash F-21 in the display. I couldn’t even get the control board to go into diagnostic mode.
Using my keen Samurai Insight®, I unplugged the washer and removed the molex connector from the water level switch (also called a pressure switch). To get to it, remove the top panel by taking out the three screws in the back of the washer. The pressure switch is right there on top, as seen in the picture below:
Anyway, I plugged the washer back in and, lo!, the washer did enter diagnostic mode and the people did sing and the Lord did grin. And there was much rejoicing. Especially after I replaced the water level switch whereupon appliantological harmony was restored.
To learn more about your washing machine, or to order parts, click here.