I am having to cook for family reunion and the readout on my YS640 is not coming on. The grill seems to be on, I can hear pellets droping.
Unplug the cooker, clean out the pellets in the burn grate and try again. You always need to start a cooking session with plugging in the cooker to power. Also, never try to restart the cooker without checking for pellets in the burn grate.
That is exactly what I did. The grill was completely cleaned. Perhaps the contact in the switch are faulty. The YS640 has been running empty for an hour now and is now only at 344° it is set to 370°
I'm guessing thermocoupler. The readouts and response times can get pretty wacky if one goes out. When mine did the readout temp was going down while the digital ladders were showing it going up. My temps also would not go past a certain degree for more than an hour.
Here are the reasons a cooker fails to ignite: download/Best%20Practice%20and%20how%20to/Cooker%20Failing%20to%20Light%20.pdf
#1 reason: the cooking session did not start with an unplugged power cord, i.e., the cooker was left plugged in after the last use.