I would like to respond to a Hotline question about setting superheat on fixed orifice air conditioning systems when the weather was cool. The concern was that the contractor could not get the suction pressure high enough to correspond to the manufacturer’s calculator.
The manufacturer’s data (several sources) presume that when the air temperature is at certain listed conditions, then the ambient outdoor temperature is warmer and will provide the necessary head pressure to operate the system. There was no reference to head pressure to operate the system, but I’ll bet it was low, mostly due to cool ambient.