When performing PMs on rooftop package units in low ambient conditions, it's often necessary to jump out the thermostat at the unit to get it to come on. I was always taught to go from R to Y1 (energizes compressor) and R to G (energizes blower motor).
First question: Why does the blower motor sometimes energize with just R to Y1?
Second question: On a two-stage unit, is it unwise for any reason to jump the unit out so that both stages come on at once (in other words, R to Y1, R to Y2, and R to G all at once)?
Thanks for the help!