Our AC isn't cooling to the set temperature.

  1. We got one tech from Company-A to come and he said that the Freon is a bit low. So, on hot days, they can't keep up. But our unit has an older R22 Freon, so he can't fill it up. He recommended about a pound of R22 Freon.
  2. I got quotes for R22 Freon from a Company-B and called one. The techs from this company come and tell me that the compressor isn't working at all and that all I have is air circulation because I keep the furnace fan on at all times. They told me that adding Freon will make no difference. Their recommendation was to install a new R22 refrigerant compressor (4500 $ for 3.5 T system) or a new R410-A refrigerant compressor+AC (8300 $ for 3.5 T system).
  3. While the techs for Company-B were talking to me, suddenly the compressor kicked on and then shut off after minutes. The temperature is still several degrees above where it is set. Then they tell me that it is short cycling and nothing can be done to fix it.
  4. I looked up causes for short cycling and low freon is listed as one. I called the techs from Company-B, but they were adamant that low Freon has nothing to do with it.

Any recommendations?

  • Think I would be at least trying the freon before shelling out 4500 to 8300$, or maybe seeing what company c has to say.
    – crip659
    Commented May 31, 2022 at 18:20
  • It is cooling just not enough? Usually means the pressure is too low, not enough refrigerant, or compressor failing. They should have detected that with they pressure gauges. If you change temperature setting does it comes on. It could be also simply your temperature gauge.
    – Traveler
    Commented May 31, 2022 at 19:02
  • 1
    Company B= scam artist , your system is low and this can cause multiple problems, a 3.5 ton system will have 7-8 lbs and probably will take 2-3 lbs to bring it up to a full charge at 100$ a lb it is worth it if that gets you another 5 years of use out of the system. The problem is R22 is obsolete and what is left is expensive or reclaimed. Omg I just checked and the R22 may be close to 300/ lb , I haven’t purchased any for a few years and last knew it was 100/lb looks 3x that now
    – Ed Beal
    Commented May 31, 2022 at 19:10
  • Depending on age of the unit , it may be better to replace the AC rather than only the compressor. Anecdotal reference ; my first compressor lasted 10 yr. My second lasted 15 yr. Commented May 31, 2022 at 19:43
  • 1
    In the last 12 months, @EdBeal, everything is 3 times as expensive as it was 24 months ago. If not more...
    – FreeMan
    Commented Jun 1, 2022 at 13:47

1 Answer 1


The unit is at end of life. You were going broke running it anyway.

Well, whoever pays your electric bill is going broke running it. I find an astonishing number of homeowners have an invisible benefactor who pays all their electric bills for them! At least it appears so, since that guides all their appliance purchase decisions.

What you have there is "That 50's air conditioner". The industry was pretty lazy and did little to improve the design or efficiency of the basic products. After they started causing severe balance issues on the power grid, the government finally made them start improving efficiency.

The standard el-cheapo units have a minimum efficiency of 13 SEER these days, which is still not great.

Replace... the question is, with what?

An air conditioner is a heat pump. If you want a viewing list on heat pump technology and where it's at, here's one on the tech generally. https://www.youtube.com/watch?v=7J52mDjZzto

Here's one on just how good the state of the art is, focusing mainly on the heating mode, which is more efficient than gas at this point. https://www.youtube.com/watch?v=MFEHFsO-XSI&t=0s

And here's one on what is practical on the market (ignore all the energy policy talk). https://www.youtube.com/watch?v=43XKfuptnik

What you have now is a 2-component system: It has the compressor and freon condenser (hot part) outside in a box, and the freon evaporator (cold part) directly above your furnace in the air-handling stack. It uses your furnace's blower to push cold air around the house.

If you want cheapo, they sell a simple drop-in unit replacement for what you have now. You will need to swap both units: outdoor and furnace-stack unit, because the new refrigerants require a different unit at the furnace. However these are not terribly costly, I had one quoted for $3000 two years ago in the height of COVID shortages. (granted we were a nonprofit and the person knew we would not be open for most of a year so it could be "side work").

But these are cheap. They will be 13 SEER, the government minimum (that means 13 BTU/hour per watt in A/C mode). Or maybe 14 SEER, big upgrade not. You can get high as 38 SEER (1/3 the cost to run, obviously), and better, those are heat pumps so you are running 3-6 COP in heat mode most of the heating season (so 3-6 "watts worth of heat" for 1 watt - that's better than burning gas locally!)

Most of the mini-split heat pumps are vastly better than 13 SEER. More cost upfront, but that's mainly because curmudgeonly air conditioner installers hate new things. Oh boy, have I dealt with some of those!

It's not legal to DIY air conditioners or heat pumps, as a rule. But the newest heat pump tech has a neat trick: They supply the outdoor unit pre-loaded with extra freon (that would be in the line-set and indoor unit). You plumb up the system and then do a standard air conditioning leak test with nitrogen instead of freon. And then, when everything checks out, you draw a vacuum, button everything up and open the freon valves on the compressor unit, and it fills the lines.

Mr.Cool has a second trick where all the units and line-set piping are pre-loaded with freon and have self-sealing connectors, which means no vacuum pump and gage set are necessary. But I've heard of problems with those.

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