AC concern.
 

Hi all. So central AC is essentially a foreign concept to me. My unit is 15 years old but seems to be working fine, and I am of the mindset that if it is not broken..... BUT I notice that for example yesterday, I set the unit to 74 degrees. During the heat, it went up to 77 degrees. The house felt fine, but it seemed like the unit was not keeping up? By the evening it went back to 74. I recently had the unit inspected and topped off with the coolant. So I guess the question, is this essentially normal/expected behavior?

You should probably have a reputable company look at the system to ensure it is working correctly.

Our AC/heat pump was putting out 60 degree air yesterday. We set the thermostat to 76 and it had no problem keeping our house cool. That is normal for us but our home is relatively new (<10 years) with good insulation.

Several factors can come into play. If the system isn't working correctly then the system itself might not be getting cool enough. If the filter or coils are dirty then it might not be moving enough air. If the system is undersized then it won't move enough air. If the home isn't sufficiently insulated then regardless of how well the system works it won't be able to keep up with the heat coming in.

A reputable company should be able to tell you if the system is working properly and if the filter and coils are clean. They should also be able to comment on whether the system seems to be sized correctly. We are happy with Munn's though I'm sure there are other companies to choose from.

It could be that it is not large enough to get 74 in yesterday's heat. Since 77 was fine why not use 77?
Up North (runs in the summer) my A/C ran about 15 years. I think at 15 you are getting to the end of its life. Assuming your new A/C will run for 15 years why not get it now instead of in a year or two after it breaks down. My assumption is you will buy a new A/C one more time in your life. So why not now?

Here is a quick test. On a hot day, go to the outside unit and look at the suction line. It is the copper pipe with the black insulation. The pipe should be cold and sweating. If it is, you know that the compressor is working. If not, you may have a cooling issue.

Be happy it's working, my neighbors broke down yesterday when it was 97 degrees.

I have been told that the average life in this area is 12 to 15 years. Many may be able to go longer but you may require more maintenance. If it is within your means, I would start getting replacement quotes. Find out the comparative prices, leadtimes, possible rebates and explore the SEER rating which is basically an efficiency measure. Seer ratings have been getting higher with time.

Better now than waiting until it fails.

Perhaps consider a warranty
 

My AC unit is 13 year old - original equipment. When I moved here 4 years ago, I "purchased" a warranty (pay yearly) from Broward Factory Service. They have free seminars quite often at various restaurants. It covers repairs to A/C units under 5 tons and if they can't repair - replacement. When I signed up - there did not seem to be an issue with age of the unit. I pay them $99 a year to come out and inspect the units. They have had to replace a condenser twice at NO COST to me. The warranty also replaced a leaking hot water tank at no cost. I mention this as why replace a working unit. Other big ticket items are covered too so I suggest you check them out.

Be sure the house does not have one of those "energy saving" gadgets on it that limits your unit at times of high demand (like when its very hot and everyone's AC is running). I had one previously in VA and the house would sometimes get a little warmer as you describe and I can only guess if there were true savings. I'd rather be comfortable.

If the refrigerant was low, you probably have a slow leak. I agree with other posters that you should consider buying a new system. I would also evaluate the size of your current system to make sure it is not undersized. You may need to upgrade to a larger size unit. It may help to compare the size of your unit with other similar size houses in your neighborhood. Typically, you need at least one ton of cooling for every 600 square feet of living space. If you don't know the unit size, write down the model number on the outside unit and look it up on the manufacturer's website. Good luck.

Yep that part I have covered. 2 Ton.
I have scheduled an appointment with home depot to send someone to investigate and size one up. I would like to think I can even get a more efficient unit than a 15 year old system.

Two tons is a pretty small unit. I would get at least 3 quotes for a new system. Two good companies are Munn's and Chuck Farrell. If I needed a new system, I would use Munn's as long as they were reasonably competitive. They are very responsive when you need a warranty repair, even on weekends. A new system will come with at least a 5 year warranty, so you want a responsive contractor. I would not buy a home warranty or separate maintenance agreement.

It's only a Patio Villa, 1100 sqft

Chuck Farrell wasn’t taking new customers this year. We have used him for our house since 2012, but had not had him work on our other homes. When I called, even though a current customer they would not make an appointment for our other 2 houses.

In my experience, my 15 year old A/C unit started to do the same. It wasn't broken, and would work just fine in the evenings, but just not able to cool like it used to on the hot summer days. These days equipment is not always readily available...so I opted to replaced it sooner than later. I had to wait a month, but a friend had to wait two months for the new one to arrive.

It sounds like you have the proper size. The courtyard villas in my neighborhood have similar units. The 2 bedroom villas, which are about 1200SF have a 2 ton unit, and the slightly larger 3 bedroom villas have a 2.5 ton unit.

I read this thread with great interest.
Yesterday I noticed when my AC was set at 77, the temp was high at 79 in the house.
I'm having Munn's coming for a checkup in July, so I'll know more then.

I heard nothing but good using Munn's from my neighbors and friends.

They should be able to tell me the life expectancy of my unit.