A pressure switch error on a Trane furnace may lead to a very cold home if not corrected in a timely manner. A pressure switch senses pressure within the flue system. The sensor closes when the furnace kicks in and allows heat to enter into the home. When a pressure switch error occurs the system will shut down and no warm air will enter the home. This switch helps protect the system from overheating and damaging the furnace. Troubleshooting tests must be run to locate the reason for the pressure switch error.
Remove the front access panel of the Trane furnace to access the pressure error switch.
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Unplug the 24-volt wires from the pressure switch.
Connect the ohm meter to the pressure switch. When the system calls for heat and the inducer fan begins to run, check each pressure switch terminal. The ohm meter should read very close to zero. If the ohm meter comes back with an open line reading, the switch is bad and needs replaced. If the pressure switch is functioning properly, other problems may be a plugged vent piping or the inducer fan.
Turn off the furnace and let the system cool down completely. Check the inducer fan, which is the circle fan located above the pressure error switch. Spin the fan manually. If the fan is not easily spun or there is water present, the inducer fan motor may need to be replaced. If the fan spins freely when tested, move onto the next step.
Check for obstructions in the venting pipes. Common obstructions include birds nests, wasp or bee nests and leaves clogging the vent piping. Remove any obstructions from venting pipes and verify if the error goes away. If after checking the switch, the inducer fan and venting the still receiving the pressure switch error, contract a HVAC professional to inspect the system.