This tripped me up for a minute until I grabbed the diagram...That'd help eh lol! Make up air was heating prior to PM. Found damper actuator was not opening afterwards and making this sound. Manually drove it open and disconnected power to keep dampers wide open. Now, heat wasn't firing but pilot was lit and MV terminal on the igntion module had power leaving it. The diagram showed the damper actuator end switch was wired between MV of the module and MV on the gas valve. Although the actuator was fully open, the switch didn't close. Bypassed the switch for now until we can get the actuator replaced. For the kids...Damper actuator end switches verify the damper actuator has fully opened. But I don't like how they wired this one. Happy HVACing #teachme

Posted by HVAC Know It All at 2021-03-17 21:35:21 UTC