Furnace Not Heating Due to Pressure Switch Fault

The pressure switch is a safety device that confirms the draft inducer is successfully venting exhaust gases. If the switch fails to close, the furnace will prevent the burners from firing. To diagnose this, inspect the flue pipe for blockages, check the condensate drain for clogs, and inspect the small rubber tubing connecting the pressure switch to the inducer assembly for cracks, kinks, or water accumulation. If these are clear, the switch itself may be stuck open.

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