HP LV Power Relay

Each DX2W-2 control module contains a DIN mount relay used to remotely power the outdoor heat pump defrost board.  This is done so that the defrost board can be remotely reset over the internet or by the control program.  To diagnose a faulty relay you can check the resistance of the coil and then if it has a resistance you can power it temporarily using 24VAC and check for continuity between NO and COM load terminals and for continuity between NC and COM load terminals when coil is not energized.