If the light flashes red 7 times, the furnace is not sensing flame. Check for a flame sensing rod (small steel rod in the path of the main burner flame). If you can see it, shut off the furnace, and clean the rod with a rag soaked in vinegar. Turn the furnace back on and see if this cures yyour fault. Make sure you turn the power off to the furnace and then back on as this will reset the circuit board.
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If the light flashes red 7 times, the furnace is not sensing flame. Check for a flame sensing rod (small steel rod in the path of the main burner flame). If you can see it, shut off the furnace, and clean the rod with a rag soaked in vinegar. Turn the furnace back on and see if this cures yyour fault. Make sure you turn the power off to the furnace and then back on as this will reset the circuit board.