Air conditioner maintenance

We had a guy out to the house yesterday to “tune-up” the AC. On the invoice, he wrote that the R22 is “a little low” but he didn’t really seem that concerned about it. He wrote that it would cost $303 to recharge it but he didn’t push it on my wife.

So should I be concerned? Is this something I need to take care of ASAP? What are the consequences if I don’t?

I am not an expert, here is what I remember back when I owned homes: R22 is the refrigerant AND lubricant within your AC system. If the level is ‘a bit low’ but it still runs you should be fine. It sounds like your repair man was a nice honest fellow, alerting you to a potential issue in a year or two but not trying to cheat you now.

Try to pay attention to your AC system as the year goes on - if it stops cooling so well, or runs all the time, then you will need to have it worked on. If it runs out of refrigerant than the compressor will seize and then you will be replacing your whole AC.

Either way it is likely a gradual issue (even a good closed loop system will likely have a little loss somewhere) and you should not be surprised.

I’d say run with it & call the guy back next year. He can compare notes and you will be prepared for the $303 cost, if needed.

I think most AC units have pressure switches: if the compressor is unable to build downstream pressure to a sufficient level within X amount of time after turning on, it knows that there’s inadequate refrigerant (and therefore inadequate lubricant) to safely run the compressor.

Before that happens, the refrigerant level will get low enough to cause the thermodynamic conditions in the evaporator coil (the part of the system that gets cold and cools your house air) to change: it will start to operate at a colder temperature. Under normal conditions, warm/humid house air passes throug the evaporator coil and deposits condensation (liquid water), which runs off into a drain. When the evaporator starts running at temps below 32F (because of low refrigerant levels), that condensate freezes on the evaporator coil. After a little bit, there’s enough frost to actually block the airflow. One of these days you’ll notice that your compressor has been running for a very long time and your house isn’t cooling, and if you go and put a hand over one of the air registers, you’ll observe very little air flow - because frost has blocked airflow through the evaporator. That’s when you know it’s time to add more refrigerant.

And the reason you need more refrigerant because there’s a leak. So the technician will also add a leak-stop chemical along with the new refrigerant, which plugs up tiny cracks in the system. We had this done to our central AC unit in 2007 (when the evaporator started frosting up as described above), and it’s been running fine ever since, now 20 years old.

“We had a guy out to the house yesterday to “tune-up” the AC.”

Did this tune-up include examining (and if needed cleaning) the evaporator coils? If the evaporator coils weren’t touched, then (to me), you didn’t get a full tune-up.

Much like a car tune-up can mean a whole range of different things to different people, so can an A/C tune-up.

Clean coils prevent your A/C system from overworking. Search for “dirty evaporator coils” or “how to clean evaporator coils” to get an idea of how much dust can build up in your A/C system.

And R-22 aka Freon is being phased out, causing R-22 prices to rise…so it may, or may not, be worth your while to see if your system has a leak and if so get your leak plugged.

and as with everything, get multiple quotes from different providers…prices and quality are all over the map.

Dirt is usually the biggest culprit in an AC not doing its job. One of the best and most important tasks you can take on yourself is to clean the cooling fins of dust, pollen, leaves, spider webs, and dirt. For a heat pump, this is as simple as turning your hose on, sticking your thumb over the end to create a strong stream, and hosing the crud off the fins. Your compressor will run less frequently, your unit will cool more efficiently and your electrical bill will go down. Same applies for a window shaker. You may have to pull the unit out of its casing to get to the fins, but it really needs to be done. Also make sure that the condensate drain hole is not plugged.

R22 is a refrigerant not a lubricant. Oil is the lubricant in AC systems.
AC systems have high and low pressure cut out safeties.

A little low could mean from 1 oz to pounds low.
a little low can cause the system to not be at max efficiency. Just have the unit serviced again next year.

Have a good friend who’s an a.c. tech. His advice to me was: 1. change the filter regularly,
2. spray down the outside unit well on a regular basis. Pref inside to outside. Get the dirt out of the base
3. Never let anyone do pressure tests unless something is wrong. Every test causes a loss of refrigerant as some needs to go into the gauge. And while an old Schrader valve is fine of left alone, they can start leaking every time you mess with it due to the aging rubber.