Apply creative thinking...
In 2001, I was riding pax in a Continental ATR, CLE-ALB. Summer heat wave. Had a MX problem starboard side before engine start, so standard ground AC yellow hose (or "hotel" mode or whatever) could not be connected/operated (got in the way of the mechanics at work). Got pretty toasty in the cabin.
Crew eventually opened the forward baggage door (port side), horsed the big old ground AC hose around into the baggage compartment, opened the connecting door from baggage area to cabin (and the rear cabin door) and cooled us all off right quick.