Wasn't the number of flashes indicating phase failure? Three flashes is a
failure of the three phase nonlinear modulated time adjusted signal from the
power company. Most new furnaces will handle up to 8 phase, and the really
good ones will up to 11 phase.
A really good technician will have a diagnostic computer, that hooks up to
the lateral data port, on the thermostat board. Interviews the furnace
without having to go to the cellar, and take the cover off.
Of course, we could be joking.
Christopher A. Young
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