We had the air conditioning installed in April (when 3 deg C outside).
The installers (did an excellent work btw), mentioned to me before they left that they charged the unit with an approximate quantity of refrigerant, as the proper pressure and function could not be confirmed at 3 deg outside temperature, and I have to call the office to set up an appointment to have the pressure and efficiency checked when it is hot outside. It's now August and the office (Christine) would schedule appointments with 3 weeks delays which won't be kept - blaming the service department as a separate entity on the basis that the unit "works". Period. Paid more than $4000 for a top efficiency unit only to just cool... which it does, but with an efficiency of a low end unit . It takes 2.3 hrs+ to cool by one degree.
I recommend if you hire them, do it through Home Depot so there will be someone to chase their behinds for warranty and follow up service.