If the door of the Lennox G16 is removed, thus the door interlock switch unpressed and system off. Does this mean that I only need to shut off the AC power from the outside breaker panel and leave the main breaker on? If not, how about I only remove the wall power plug for the furnace?
Other people can still have power while I service the furnace. I need to do some rewiring for my thermostat.
As I commented, my G16s have a hardwired power switch on the side. Or as others suggested, you should figure out which breaker controls the furnace circuit, and turn it off. (You should not have to shut off the main unless you are working inside the panel box itself)
But after looking over the wiring diagram for my G16, it does seem that the door switch does break the AC hot before it connects to anything else (including the thermostat transformer). So if you kept out of the blower control box, you would be safe to work on the thermostat and related wiring.
There's a breaker that feeds the fan junction box in your furnace. There's usually a regular plug in near your blower unit that can be unplugged. This is the circuits that feed power for blower fan and 120/24 volt transformer for the stat
