Figured you would know this. Just bought a lincoln 255 mig welder , it is a 2003 model. The unit states it has fan on demand, but the moment an arc is struck the cooling fan comes on. Is this normal for the 255. I have not let the machine sit with the fan running for any length of time to see if it turnd off. It turns on the fan regardless of voltage setting, and shuting the machine off then on turns the fan off. Seems to me it has a bad thermostat?