PSA: Double check that sensor magnet polarity before you leave

Got a call back on a duplex in Tucson three days after install. Elderly lady swears the alarm goes off every time the sun hits the window. Drove back, pulled the door sensor, and the magnet was flipped upside down. The reed switch was picking it up intermittent when the temp changed. Reversed it and zero false alarms in two weeks now. Anyone else run into polarity sensitivity on cheap door contacts or is this just a me problem?

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oliver24d ago

Funny how tiny stuff like that messes everything up, same thing happens with my garage door opener when the battery gets low, it acts like a ghost sometimes. Guess polarity is just one of those silent troublemakers nobody thinks about until it bites you.