I actually don’t know the brand name of the units we buy, but here’s some thoughts – we’re in Texas:
– I’ve never bought the unit & then hired the guy to install it later, but we do have used units that we call the experts to install.
– For new units, we have found StyleCrest to be competitive. They have the materials (units) and they will get someone to do the installation as well. We have found them to be competitive with the local guys, but we sometimes use the local guys anyway because they will come out to do repairs &/or install used units more readily if we do the bigger jobs through them also. [We get used units that we need to install when we get used homes and bring them in to the park. We have purchased used units on occasion, but we try to stay away from Freon-based units which can be had for real cheap; there’s a reason for that, see below.]
– Don’t buy a bigger unit (more tons) than recommended for the unit (mfr’s recommendation) even if it’s a hot region. I forget the exact reason, but it has to do with the A/C taking out humidity rather than just cooling the air. If the unit is too big it takes out too much humidity and the temp won’t be right for the relative humidity that you are expecting. Most of our homes are about 1000-1200 sq ft and take a 3, 3.5, or 4 ton unit.
– I believe that A/C has to be installed by licensed people because of the refrigerant, which is bad for the environment. I believe there is a special extra license for the old Freon (R-22?). Used Freon-based units are much cheaper but Freon is VERY expensive. New units are never Freon, but sometimes you have to decide whether to fix an older unit or replace it. I think the new units are R-410a. The parts are not compatible.
– Central A/C is a lot more expensive than several window units; I think we pay about $2500 for an installed 3-ton. That’s about $1k for hookup & $1,500 for (new) equipment. You could install a lot of window units for that price. But, window units are a lot easier to steal.
– We are CONSTANTLY fixing fan motors for the condenser and capacitors (located outside?). I think the rain gets into them and they fail a lot. We also replace a lot of pumps (also outside in the condenser?) and thermostats. If you can do this yourself, you would probably save a lot of money. You don’t want to mess around with the refrigerant in the tubes though.