actually, i should point out that i don't know where the thermostat is. i'm assuming it's measuring the temperature at the cold air return (you'd think modern furnaces are high tech about this, but i don't know); if the thermostat is away from there (like in his living room, for example) then it shouldn't have that kind of feedback problem.

given that the furnace is in his kitchen, though (yes, for real, there's a furnace in the kitchen - good luck renting that unit in the future, too), it seems likely to me that the thermostat is probably connected directly to it....

i mean, i wouldn't expect them to chop through the walls to place the thermostat five feet away in the other room. it's probably mounted right on it.