I have two heat pumps, one for the first floor, one for the second floor.
They are identical as far as I know. The outside units are located side by
side (about 3' apart). Recently I noticed that, on humid days, when frost
forms on the outside units, one of them will have a uniform layer of frost
from the top of the coils to the bottom, while the other has frost only on
the top 3/4 of the coils. Might that indicate a less than full charge on
the unit that develops no frost on the bottom 1/4 of the coils, or any other
problem? Or is it normal? I've lived in this house less than two months,
after 19 years in a house with gas forced air heat, so there's a lot about
heat pumps I don't know yet.