Tony Cox wrote:

snip
I just draw a blank on this. Unless there is a heat source near
the selector. Then I can rationalize an explanation. If there's some
venting/plumbing explanation, I'd expect some admonition to
"select the fullest tank" or "don't fly above 5000' without more
than 10 gallons in a tank". Makes no sense as is.

tc

As far as I can tell there is no heat source anywhere near the selector.

One day I'll get the real story, until then....I'll just select L or R above
5000' and chalk it up to one of those mysteries of the universe.
--
Frank....H