A defective flow switch will cause a "Flashing Flo" or even a "Solid Flo" on the Control Panel Icon. "Solid Flo" is the Flo Switch, a "Flashing Flo" could be: Flo Switch, Circulation Pump(clogged or defective), Dirty Filter.
The connectors on the Flow Switch are attached to a pc board connector that is located on the PC Board (usually at the top). There are other wires connected to this plug: Jumper interlock wire,Flow Switch, High Limit and Temp sensor. Remove the pin connector from the board . To remove a sensor or switch wire from the sensor harness connector, insert a paper clip into the slot corresponding with the wire to be removed. This will depress the pin tine, allowing the wire to be pulled from the harness connector. Important! When reinstalling the sensor or switch wire back into the sensor harness connector, make sure the pin tine is lifted (approx. 1/32" prior to inserting the wire. This will insure the sensor wire locks into the harness connector. Do not over bend the pin tine or it may break off.