Check for which Pump is Plumbed through the Heater.
(Circ Pump, 2-Speed Pump 1 Low, or 1-Speed Pump 2)
Check the Wiring Diagram inside the System Box Cover, and the following appropriate Hot Sheet for the Correct Pump and Heating Related Dip Switch Settings, based on the Heating Related Pump in Step 1. above.
At the Dip Switches on the System Board, Verify that the Pump and Heating Related Dip Switches are Set Correctly.
If they are Not Set Correctly, Set them Correctly Now.