I suddenly had a problem today. I use the unit in F. Today I started the hot air and it flashed C. I hadnít had a power loss or anything. I unplugged the main and turned the temp dial to set F. I plugged the main back in and F was now set. I turned the temperature knob to where I generally have it and it was climbing to well over 600 f and climbing. I turned it down and the very lowest setting is showing around 400 F. I tried the soldering iron and it is doing the same. I have unplugged and plugged it back in with the same results. I have also set it to C and it is way out as well. Any suggestions?