The $5,000 AC rule, explained

Running the numbers

System age	Repair quote	Age x cost	Rule says
6 years	$300 capacitor	$1,800	Repair
12 years	$450 contactor	$5,400	Price a replacement
14 years	$2,200 compressor	$30,800	Replace

Illustrations only. Each repair figure falls inside the national bands Fixr and This Old House publish; none is a quote.

The blind spots

Small parts on old systems trip it too easily. Look at the middle row: a $450 contactor on a 12 year old unit scores $5,400, yet if that unit otherwise cools and dries the house, replacing a switch and starting a replacement fund is often the sensible move. Treat a fail as a reason to ask for a second number, not as a purchase order.

It also knows nothing about how a Greenville system lives. A heat pump that heats the house all winter has logged far more hours at 12 than an air conditioner of the same age in a house with a gas furnace. The formula can't see whether the unit still pulls the house dry on a muggy night (the Greenville station now records about 53.2 nights a year with a low of 72°F or above), whether the ducts under the floor are leaking, or whether this is the third repair in three summers.

How I'd use it here

1. Do the multiplication on the repair you were quoted.
2. Over $5,000? Ask the same company, or a second one, for a replacement price on the same visit.
3. Read what the replacement price covers: the North Carolina permit, duct sealing if any, and the refrigerant in the new unit.
4. Pick your season if you can. An April or October install is calmer than an emergency one in July.

The full repair or replace guide.