I have a kitchen vent made by Dacor that, when in use, rises up out of the
counter at the back of the cooktop. It is a snazzy design, but my unit has a
problem with the lower fan speeds after a few minutes. If I can get a
schematic for the fan control circuitry, perhaps I can figure out what is
the problem. Even a service manual would be helpful.

Dacor says that a schematic is not available and keeps referring me to
nearby service personnel. Unfortunately, we are in a rural area and the one
service group that looked at it when it still was under warranty was not
able to fix it. As an electronics engineer, the problem appears to be an
intermittent component, most likely the SCR or its control circuit, since
everything works fine for a least a minute or so when first used.