So, naturally I respond with, “you don’t tell your doctor which medication to prescribe you, do you?” The point is, on the residential level, who you get to install your HVAC unit is far more important than which unit you choose. Keep your options open and let your HVAC contractor make a few recommendations – that’s why you spent time finding a reputable contractor!
Central home air conditioner service systems consist of two major components: a condensing unit that sits outside your house, and the evaporator coil (often referred to as an A-coil) that sits in the plenum of your furnace or air handler. The refrigerant in the A-coil picks up the heat from your home and moves it to the outdoor condensing unit. The condensing unit fan blows outside air through the condensing coil to remove the heat. The condensing unit houses the three parts replaceable by a DIYer: the AC contactor, the start/run capacitor(s) and the condenser fan motor. The condensing unit also houses the compressor, but only a pro can replace that. The A-coil has no parts that can be serviced by a DIYer.
If the AC doesn’t turn off, it may be time to clean the condensing unit. Dirty condenser coils won’t give off heat efficiently and will keep the unit running. Another possibility: The contacts on the outdoor run relay may have welded together—something that can happen over time because of frequent electrical arcing at the relay. Before checking the run relay, turn off the power to the furnace and the condensing unit. Next, disassemble the relay and pry apart the contacts. This should do the trick until you buy a replacement—which you should do soon.
Two weeks go by and no phone call from HVAC Service regarding install date, or any update at all. I call them to check in to see if they have put me on the schedule and when I can expect to have the AC installed. You can tell by the discussion I had with the lady on the phone that they completely forgot about me and have not scheduled anything. She says she needs to get in contact with the owner because she has no idea on the availability of the crane. I was told that she would call me back by the end of the day with an update. Surprise, surprise, no phone call.
Before opening the electrical cover on the A/C unit, be sure to shut off all power to the compressor unit and the indoor furnace or air handler, and verify that it is off. Note that this may mean shutting off a circuit breaker that serves the furnace and air handler, and then, near the compressor, pulling out the disconnect block (or shutting off the 220-volt power) to the outdoor compressor.