Proactively replace 21 year old central air or wait until it dies?

[G-String]

My current central air unit is now 21 years old but works fine. Would you recommend I purchase a new unit proactively, or wait until my current unit dies?  If I wait until it dies in the middle of summer, I will likely pay more because of demand.  By replacing it proactively in the offseason, I will get a better deal. The downside of proactively replacing it is my 21 year old unit may last another 10 years and I could have moved out of my current home by then, thus wasting money. 

Do central AC's usually die instantly, or do they sort of fade and/or show signs of dying, before they actually die?

[curious_george]

I think this sort of depends on how dependent you are on the AC.

Where I live in the Midwest, I would wait for it to die. We don't really need AC, my family and I are all well adapted to the heat because we go outside often in the summer time.

We also have a basement, fans, and live in a very well insulated house. So we can afford to have our AC die and simply wait until the off season to have it replaced (which is exactly what we did actually).

If I lived in Phoenix Arizona, or Texas, or if my kids were not adapted to the heat, or we had no basement, fans, mist fans etc, I would be more proactive.

So - I think it just depends on how much you need the AC and if you can go without AC and wait for a good price to have it replaced or not.

ETA: My AC died suddenly because the compressor died. It really depends though on what part failed, which determines if it will die suddenly or slowly. Also a lot of things like fans, capacitors, etc can be fixed to prolong the life of the AC. But it's nearly impossible to get parts unless you're a certified HVAC technician.

[Cranky]

21 years is a good run for an a/c, but not remarkable. I wouldn’t replace it yet if it’s functioning well, but I might pay for a service call where I would find out if it’s fully charged, etc. That would also mean that you have an established relationship with a service company in case it gives out during a July heat wave when it can take quite a while to get it looked at.

My a/c is a good 30 years old and limped through the summer, so I’m going to get some estimates this fall.

[2sk22]

We have a Lenox Pulse furnace that is 27 years old and is still running just fine! It's not the quietest unit (sounds a bit like a 2 stroke motorbike when running) but it does put out a lot of heat. I will definitely replace it with a heat pump when replacement time comes however.

[ChickenStash]

For me, I would not replace it until it dies and a repair is not reasonable. I've had mine go out and it took me a week or two of 85-95* days to get parts fix it (DIY, so kinda slow) and it wasn't a big deal. But, this is in the midwest so summer isn't too terrible.

As to whether they die fast to slow, it depends on what fails. If there's a slow leak, you'll usually just see longer run times and poor cooling for a while before it loses enough to trip a cut off. Capacitors or contactors might show as intermittent no-starts before they completely fail but that's hard to notice. Controller or wiring issues will probably be a fast death. Compressor failure might make some nasty noise before it goes, or it may just lock up one day.

For a free health check, pull the cover off the outdoor unit and inspect the wiring for rodent damage or any rub through spots (this killed the controller board on mine after ~12 years). Look for corrosion, crusty secretions, and swelling on the capacitors (had to replace the caps on mine at ~10 years). Make sure the coils are clean - outdoor and indoor if you can get to them.

Beyond that, paying a service call to do a pressure check, as mentioned above, is also a good idea to get a handle on the overall health.

 

[Dreamer40]

I’d wait longer for a sign that it’s starting to fall apart. Mine is around 15 years old and we had to replace two separate broken parts last year. We were out of AC at least a few days each time when it was unbearably hot. We thought about replacing the whole thing this winter but might still wait because I’ve had other house expenses lately. But it’s going to happen soon.

[Louise]

I'd wait a bit longer too. We've been pondering the same question with our furnace. We live in a cold state and it's over 30 years old. We keep procrastinating on the replacement saying "let's just get through one more winter." We've been saying that for at least the last five years. I probably just jinxed myself lol.

[LifeHappens]

Have you had it serviced recently? Most HVAC companies will do a tune-up for a pretty reasonable fee and will let you know if anything looks suspect.

[G-String]

Have you had it serviced recently? Most HVAC companies will do a tune-up for a pretty reasonable fee and will let you know if anything looks suspect.

I bought the home 7 years ago and have not had a tune-up in that time.  AC appears to be working the same now as when I bought the home. 

[Laura33]

I wouldn't rush to replace it if it's working fine.  We haven't been able to find any truly reliable AC system/vendor; everything seems to go out within 8-10 years.  So if you have one that is still chugging along, I'd be loath to give it up until necessary.

One thing to keep in mind/investigate, though, is that there are new restrictions coming on refrigerants.  Your system probably uses R22 given its age.  That is becoming more and more restricted and thus will cost more and more.  If and when you get the point of having to recharge the system frequently, you should replace it, because R22 leaks are pretty damaging to the environment, and because replacing it will cost a pretty penny.

While you have time, why not do some research into what new non-R22 systems might be available and how much they might cost?  If the AC goes within the next couple of years, you could probably still get an R22 system, as various new restrictions will be coming over time vs. immediately.  But if you want your new system to last another decade or two, might as well plan for those future restrictions.

[G-String]

I wouldn't rush to replace it if it's working fine.  We haven't been able to find any truly reliable AC system/vendor; everything seems to go out within 8-10 years.  So if you have one that is still chugging along, I'd be loath to give it up until necessary.

One thing to keep in mind/investigate, though, is that there are new restrictions coming on refrigerants.  Your system probably uses R22 given its age.  That is becoming more and more restricted and thus will cost more and more.  If and when you get the point of having to recharge the system frequently, you should replace it, because R22 leaks are pretty damaging to the environment, and because replacing it will cost a pretty penny.

While you have time, why not do some research into what new non-R22 systems might be available and how much they might cost?  If the AC goes within the next couple of years, you could probably still get an R22 system, as various new restrictions will be coming over time vs. immediately.  But if you want your new system to last another decade or two, might as well plan for those future restrictions.

Great points. I live in Canada and unfortunately R-22 has already bene phased out here and is almost impossible to find.

[alsoknownasDean]

The other question will be whether you wish to replace like with like or whether you want to get one you can also use for heating.

Probably worth getting it inspected/serviced by a professional to see whether it's still in good condition or not. Especially if it's paired with a gas furnace and hence has the additional risk of gas leaks/carbon monoxide.

Definitely don't want the risk of leaks given R-22 has a global warming potential of around 1810 times that of CO2.

[GilesMM]

The other question will be whether you wish to replace like with like or whether you want to get one you can also use for heating.

Probably worth getting it inspected/serviced by a professional to see whether it's still in good condition or not. Especially if it's paired with a gas furnace and hence has the additional risk of gas leaks/carbon monoxide.

Definitely don't want the risk of leaks given R-22 has a global warming potential of around 1810 times that of CO2.

On the other hand, newer units use r410 which is even worse than r22.

[Loren Ver]

Since ours was still working okay we waited until the government gave a credit for replacing the furnace with a more efficient one which got us the AC for almost free.  We waited until the credits were going to expire and then replaced both units.

Not sure when we might have an administration that will be giving out good deals, but if it doesn't hurt to wait why pre- buy for no reason. 

Loren

[bill1827]

The other question will be whether you wish to replace like with like or whether you want to get one you can also use for heating.

Probably worth getting it inspected/serviced by a professional to see whether it's still in good condition or not. Especially if it's paired with a gas furnace and hence has the additional risk of gas leaks/carbon monoxide.

Definitely don't want the risk of leaks given R-22 has a global warming potential of around 1810 times that of CO2.

On the other hand, newer units use r410 which is even worse than r22.

Over here new units commonly use R32 and the best ones use R290 (propane) which has a very low GWP.

[jnw]

We used ours until it died.  About 3 days of heat in June.. if it was in July or August we would of had to stay in a motel.

They were going to replace it keeping the old copper line in place, I paid an extra $200 for them to put new copper in.

[K_in_the_kitchen]

We replaced proactively, but it was a 32 year old unit and we’d been limping it along for a couple of years.  We decided to replace it when we were also having the roof replaced.  Where we are, we would have to find someplace else to stay if the A/C went out in summer.

[Sibley]

Oh, hi! You are me in the past. My plan was to replace my 20 year old AC and 30 year old furnace in spring 2024, based on the increasing repairs that both units had needed. Then the ac decided to die rather suddenly and thoroughly days before a massive heatwave. I had to scramble to assemble temporary cooling, it simply would have been too hot in the house with nothing. There's a thread somewhere if you're interested.

Anyway, I got a new heat pump and furnace this year. I would have preferred to schedule for spring, but even though it was the end of summer I could easily have still needed ac. And I certainly was not going to disturb a 30 year old furnace which already had some minor issues. But my risk tolerance for hvac failures is fairly low.

Are you doing regular maintenance on the unit? If so, what have the results been? How dependent are you on ac?

As for wasting money, you would probably get a lower price on the house with a 20+ ac unit, so it might not be as much of a hit as you fear.

[Dicey]

Be aware that the people who offer "free" or really cheap check-ups may well be trying to sell you a new unit. Just a heads up.

We have rental houses with elderly tenants in the Desert. We use a local sole proprietor for our maintenance and replacements. Way more reasonable than the corporate outfits.

[Dicey]

Be aware that the people who offer "free" or really cheap check-ups may well be trying to sell you a new unit. Just a heads up.

We have rental houses with elderly tenants in the Desert. We use a local sole proprietor for our maintenance and replacements. Way more reasonable than the corporate outfits.

HaHaHa, right after this post one of the rental HVAC units crapped out. We called our sole proprietor and it was replaced in 36 hours. It cost $5,500, but it was the oldest one in our fleet and we were expecting it to go any day.

[La Bibliotecaria Feroz]

I consider proactive replacement when I want to swap with something different.

We had some trouble with the water heater. We decided to go ahead and replace it even though it might have run for a long time more, because we wanted to replace it with a heat pump water heater and that required an upgrade to our electrical panel. And that takes time! Next year we are going to replace the furnace and AC with a heat pump proactively.

(Proactively replacing furnace might seem extravagant but: 1. Our basement is 10 degrees colder than the upstairs and almost impossible to heat above 61 degrees and YES I know basements are hard to heat and why but I really think we can do better with a system that's better for the space and 2. Aside from the environmental impact of natural gas [our electric is all solar and wind], my husband can't smell it and he is often home alone with our baby for hours at a time. Also 3. at least there will be rebates for it.)

[G-String]

As an update: I had a HVAC technician come by and inspect the unit and run some tests.  It is not in brand new condition (obviously), but everything is within normal/functional range.  The HVAC guy said there is no rush to replace it. 

[Dicey]

That's great news! Our library was built in the late 1970's and still has the original HVAC system. The money's finally been scrounged up for a new system. No one's taking bets on how long the new system will last.

[NV Teacher]

I would wait until it dies.  We have a coal furnace that is 60+ years old and runs like a champ.  It is essentially a simple machine with an auger and some fans.  We do basic maintenance in the fall before starting it up for the winter.  It provides consistent even heat in the winter and the price of coal is very reasonable considering it runs about six months of the year.  Doing regular maintenance will typically extend the life of most pieces of equipment.

[BlueMR2]

Ours died a sudden death, no warning.  I've been told that the typical lifespan of whole house A/C is around 10 years before major repairs nearing the cost of replacement are expected.

[GilesMM]

Ours died a sudden death, no warning.  I've been told that the typical lifespan of whole house A/C is around 10 years before major repairs nearing the cost of replacement are expected.

Sounds like you have been talking to a profitable HVAC company!  They make most of their mark-up on sales and installation of new equipment and would love to sell you a replacement.  10 years is really short.    AC condensers should definitely last 15-20 years.

[FINate]

One thing to keep in mind/investigate, though, is that there are new restrictions coming on refrigerants.  Your system probably uses R22 given its age.  That is becoming more and more restricted and thus will cost more and more.  If and when you get the point of having to recharge the system frequently, you should replace it, because R22 leaks are pretty damaging to the environment, and because replacing it will cost a pretty penny.

This^^. We had a ~20 year old AC that worked but wasn't cooling great. Had it tested and it needed a recharge of R22. We did that once in the spring and it worked great that summer, but then it needed another recharge the following year. So we replaced it. Too expensive to keep adding R22 and also bad for the environment. Whereas if the unit isn't leaking refrigerant I would keep fixing mechanical/electrical components as needed to keep it going -- these are pretty simple devices.

[reeshau]

I suspect the 10 year figure may have origins based on the warranty period:

https://www.trane.com/residential/en/resources/warranty-and-registration/

https://www.lennox.com/residential/owners/assistance/warranty/

https://www.carrier.com/residential/en/us/homeowner-resources/warranty/

But yeah, 10 years would be a big problem.  I have 2 brothers in the business, and they definitely do not want to be seeing 10% of their customers on an emergency / large project basis every year.  Particularly because failures at that kind of time frame would probably be discovered when the system is needed, I.e. hot weather.

[Fomerly known as something]

I’m waiting for both my water heater and central heater to die, both are ancient.

[Cranky]

21 years is a good run for an a/c, but not remarkable. I wouldn’t replace it yet if it’s functioning well, but I might pay for a service call where I would find out if it’s fully charged, etc. That would also mean that you have an established relationship with a service company in case it gives out during a July heat wave when it can take quite a while to get it looked at.

My a/c is a good 30 years old and limped through the summer, so I’m going to get some estimates this fall.

Update. My elderly a/c was replaced last month and is humming along through the heat wave! I’m happy to have that done on my time schedule.