Suburban Furnace has 2 Amp Phantom Load when off

DC is always AT the furnace
Comes from the FUSED Source (DC Dist Panel) to the furnace controls
Furnace controls would be either a 'Timed Delay Relay' OR 'PWR' circuit on the circuit board (model/vintage dependent)
DC also goes to the Thermostat

2A Draw is high when not running

Find/ID the Source Fuse and see IF it is being used for something else then just furnace

Furnace motor can draw 8 - 11.5 Amps (Model dependent)
But only when running

See Pgs 34 - 36 for wiring diagrams

Suburban RV Furnaces