I have a similar problem. Temperature alarm on my DF 40 from 1999. Has been going on for the last few years on and off. Impeller changed last year and cooling appears to be fine judged by the temperature on the "control water" (don't know in English). Thermostat removed and tested. Although I couldt check the exact temperature for opening, I could certainly see it opened. The problem with temperature alert prevails even when running the motor without the thermostat, so now I'm quite helpless... Anyone knows if this may be fixed easily, or do I have to have professionals look at it?
