"John Clonts" wrote in message

Maybe it was just broken and some misunderstanding or miscommunication
occurred?

I have no experience with the Saab 340, but with other tprops and a few
jets. The cooling air provided on these craft does not come from a
traditional "air conditioner" as you might be familiar with, in that there
is no refrigerant. The units installed on most of these planes are
referred to as "air handlers" or "air cycle machines", but they all
essentially perform similar functions. Hot, compressed air is bled from the
compressor section of an engine, allowed to expand, which cools it and
extracts moisture, then is recompressed, manipulated through a couple of
iterations like this to achieve certain ends with the air. At the end
point, you often wind up with very cold, very dry air, which is then remixed
with a controlled quantity of ambient air and funneled to the cabin eyeballs
as the cool dry air we all know and love.

In many turbo props at idle on the ground, there simply is not a high enough
flow of bleed air coming from the idling engine to adequately feed the air
cycle machine, and the net result is weak and inadequate air conditioning on
the ground while taxiing. This, of course, usually occurs right after the
pax have schlepped across a 90 degree ramp to get to the plane, so the
inadequacy is felt all the more strongly. In most cases, once high power
settings are achieved after t/o, the plane cools fairly quickly - which is
small solace to the already drenched passengers. Years ago when I flew a
Bandierante, we used to regularly see internal cabin temps of about 100 to
105 degrees while taxiing.