I am a General Contractor & real estate investor with a number of rental properties. I do no HVAC installations and only very minor HVAC repairs. I am from NW Indiana, near Chicago.
For many years I have been advised by my HVAC subcontractor(s) that they can not properly charge and balance the freon in the AC system unless the outside temp is about 70' Fh or higher. So on winter jobs, we generally do not set the condenser units until the Spring when we can reach the 70' temp outside. This obviously sometimes stops us from completing our jobs 100%.
Recently a number of my clients have told me that they have been advised that this is not true (can not properly charge and balance the freon in the AC system unless the outside temp is about 70' Fh or higher). If so, this makes my clients wonder why I don't know as much as they do.
Is there a difinitive answer to this question . . . . . or are there variables that can make the answer different?
Depends on the type of equipment and methods of charging. Typically older, fixed orfice, cooling only equipment you don't mess with the charge less than 65-70 degrees. The newer cooling equipment and equipment with a txv, may be able to charge as low as 55 degrees. But below that, can't charge accurately.
The systems I installed had the condensers pre-charged for a 15 foot line set, I would still connect, vacuum, and leak test at lower outside temperatures and come back in the spring to tweak the charge for the correct superheat. I just disconnect the t-stat at the condenser junction box so it can't be turned on if I know the charge is way off which it seldom was if you kept it close to the line set specs.