On Wednesday, October 2, 2019 at 12:01:23 PM UTC-4, Davej wrote:
On Tuesday, October 1, 2019 at 12:43:33 PM UTC-5, trader_4 wrote:
On Tuesday, October 1, 2019 at 1:17:18 PM UTC-4, Davej wrote:
How often do you clean your "A" coil? Never? Every few years?

Never. I have yet to see one installed on a residential central
AC where it has a means of access. Everyone I've seen, it's either
in it's own sheet metal casing that sits on top of the furnace or
it's inside a sheet metal plenum that's part of the duct work.
Neither has ever had an access panel to get to the coils. I
suppose you could cut the sheet metal and make access, as long as
you know the orientation and stay away from the coils. [...]

My concern is that the "A" coil is a moist surface. The thing could
become coated with mold and who would know? I think it is absurd
the way they are installed with zero access. Certainly an access
scheme could be fabricated.

Well, all I can tell you is that 25 years, no mold on the old, never cleaned one. Maybe the combination of it either being near freezing or hot inhibits mold.