It is your other loads.
Your air conditioner connects between hot and neutral. But it is not the only appliance which does that!
If you have disconnected the main circuit breaker, and also unplugged the air conditioner, then what remains is all the other appliances in the house which are switched on, drawing "vampire loads" or have automatically cycled on (e.g. water heater/boiler).
You are measuring the resistance across them (well, when the load doesn't have power). Many loads, like incandescent bulbs, have low resistance when un-lit, but much higher resistance when lit.
Fun with math
You could figure out the resistance of each load individually by measuring it separately... but summing up resistances is really weird. You are much better off thinking in terms of conductance. Conductance is the inverse of resistance, so take 1 divided by it. Your 10.2 ohms is 0.098 Siemens. Siemens is the unit. Really. Symbol is "S".
Probably easier to work in milli-Siemens, of which that would be 98 mS.
All of the conductances of your individual appliances will add up to 98 mS.
Measure the resistance of them individually one at a time, take 1/ohms to get Siemens, multiply by 1000 to get milli-Siemens, and add them up!
Say your water heater is 50 ohms or 20 mS, and your cell phone charger is 1000 ohms or 1 milli-Siemens, that accounts for 21 mS so far.
Again, the conductance of a dead load is not the same as when it is under power. Unless it's a heating element (toaster, hair dryer, etc.)
