The rule, in short
Replace when the system is past its age threshold - more than 10 years for an air conditioner or heat pump, more than 15 for a furnace or boiler - and the failed part is a major one: the compressor, the heat exchanger, or a leaking evaporator coil. Repair when the failed part is a capacitor, contactor, fan motor, igniter or control board, no matter how old the unit is. Those two rules settle most cases. The rest of this page is how to check each input, and one piece of misinformation to watch for.
Step 1: find out how old it actually is
Not how long you have lived there - the manufacture date. It is on the data plate on the outdoor condenser or on the furnace cabinet, usually encoded in the serial number. Most manufacturers put the year in the first four digits or the last four; if it is not obvious, photograph the plate and ask. A technician can read it in seconds and there is no reason for them to be vague about it.
ENERGY STAR's thresholds are straightforward: consider replacement once a heat pump or air conditioner is more than 10 years old, or a furnace or boiler is more than 15 years old. Those are not expiry dates. They are the point at which a major repair stops being obviously worth it.
Step 2: make someone name the failed part
Naming the failed component is the step that decides the answer, and it is the one most homeowners skip. There is a clean line between parts that are worth replacing on almost any system and parts whose failure is effectively the end of the unit.
Repair, whatever the age. Capacitor, contactor, relay, condenser fan motor, blower motor, igniter, flame sensor, thermostat, control board, condensate pump. These are components, not systems. A dual run capacitor - the most common failure on a residential condenser - retails for around ten dollars. If someone quotes a system replacement off the back of one of these, get a second opinion.
Replacement conversation, at any age. Failed compressor, cracked heat exchanger, leaking evaporator coil. Each of these is either the most expensive single part in the system or is buried behind enough labour that the repair approaches a meaningful fraction of a new unit.
The exception that is not a decision at all: a cracked heat exchanger. That crack can put combustion gases, including carbon monoxide, into the air the house breathes. Shut the furnace off and decide afterwards, not while it runs.
Step 3: the only case where the numbers decide
Put steps one and two together and most situations answer themselves. A capacitor on a 14-year-old air conditioner: repair it, and start saving. A failed compressor on a 4-year-old unit: repair it, and check the warranty first, because compressors often carry longer coverage than the rest of the system.
The genuine middle case is a major failure on a unit near its threshold - a compressor on a 9-to-12-year-old air conditioner, or a heat exchanger on a 13-to-16-year-old furnace. Three things resolve it, in this order:
- Warranty status. Check before anything else. A parts warranty still in force can move a five-figure decision by thousands, and warranties survive changes of ownership more often than people assume.
- How long you are staying. If you are moving inside two years, the repair keeps the house sellable and the buyer makes the replacement decision. If you are staying ten, you will buy the new system anyway - buying it now rather than after a second repair is usually the cheaper path.
- Whether this is the first repair or the third. A system needing repeated repairs while bills climb is telling you something a single quote cannot. ENERGY STAR names exactly that pattern - frequent repairs alongside rising energy bills - as a replacement signal in its own right.
If you were told R-22 forces a replacement
An R-22 system does not have to be replaced, and the claim that it does is the most common piece of misinformation in this entire decision. Production and import of new R-22 in the United States ended on 1 January 2020. What that did not do is outlaw your air conditioner.
The EPA's position, in its own homeowner guidance, is that R-22 may continue to be used to service existing systems for as long as necessary, and that the agency does not require homeowners to replace their existing equipment. Reclaimed R-22 and stock produced before 2020 remain legal to buy and use. The EPA does note that price and availability may change over time, and that is the real consideration - not legality.
So R-22 belongs in the decision as a cost input, not a legal deadline. If your system holds R-22 and is leaking, the rising price of the refrigerant is a fair argument for replacing rather than repeatedly recharging. "You are not allowed to run it any more" is not a fair argument, and hearing it is a reason to get another quote.
What actually drives the bill
We are not going to print one national replacement figure, because the honest answer is that system size, efficiency tier, the state of your ductwork and your local labour rate move it more than any average can carry. What is worth knowing is the shape of the invoice.
On a small repair, most of what you pay is the visit and the technician's time rather than the component - the national median wage for HVAC mechanics and installers is $29.33 an hour, and a diagnostic call is billed on top of it. That is legitimate, and it is why a ten-dollar part can appear on a several-hundred-dollar invoice. On a replacement, the split inverts: equipment and ductwork dominate, and the efficiency tier you choose is the biggest lever you personally control.
What to ask before you agree to anything
- What exactly failed? Show me the part, and write the model down.
- How old is the unit, from the data plate - not from an estimate?
- Is any part of this still under warranty, and have you checked?
- What is the repair cost, split into diagnosis, labour and parts?
- If I replace instead, is the quote for like-for-like or an upgrade?
- Does the replacement need duct work to hit its rated efficiency?
- What happens if I repair now and it fails again this season?
A technician who answers those readily is worth listening to. One who cannot name the failed part but is confident about a replacement is telling you something too.