Cause of error code STA20

Damper Failed to Open

Solution for error code STA20

The control is waiting for the damper to open. Damper end switch has failed to close (end switch contact is stuck open).  Combustion can never take place unless the damper blade is in the fully open position.  

Check the following:
During status “STA18" or “STA 20” the control terminal “P6 - 5” (yellow wire) is energized.
Check for loose connection between control and vent damper, check damper harness.
Check for obstruction in path of damper
When damper is open (end switch closed) control terminal “P6 – 2” should receive power from the vent damper.
Place jumper between control terminal P6-5 and P6-2.  If error 55 does not clear, replace control.
Defective harness or vent damper.