One of the problems with the swamp cooler system is that it is completely separate from the heating system. They have no idea when each other is on.
So, if I spend the morning up on the roof cleaning up and tightening everything on the swamp cooler to get it in tip-top condition, and turn it on without turning off the heater, voila – the heat comes on while the cooler is on.
Yup. I did that today.
Fortunately I was home, in the house, and turned it off immediately. It’s happened before, when I’ve gone out to run errands just to come home to a split-personality home fighting itself.