The Daring Dufas wrote:
Me and my late friend with whom I did a lot of residential HVAC work,
replaced more capacitors for customers living out in rural areas. When
we installed electrical surge arresters right on the metal housing of
the outdoor unit, we had no more capacitor failures.

I don't live in a rural area, but I do have a 2009 Trane high-efficiency
furnace and A/C that have a *lot* of circuit boards in them. Do you
have any experience that surge protectors on the equipment help prevent
board replacements and other failures "in town"? $40 for the Supco
SCM150 you mentioned, or for a Square D SDSA1175, seems like cheap
insurance to me.

On thing that helps a lot is to replace a 370 volt rated capacitor
with one rated 440 volts.

On the replacement I did, both the new and old were rated at 440 V.

Thanks!

Matt Roberds