What makes the A/C freeze up?

Discussion in 'Shop Talk' started by oz in SC, May 16, 2005.

  1. oz in SC

    oz in SC Well-Known Member

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    We have a VERY old A/C system(original to the house-27 years old) that has been in a dilapidated but working state for the years we have owned the house.

    It had the compressor replaced about five or six years ago and has had work done to it in the years in between as well.

    Well it has now started to freeze up now...

    We are at the point we will most likely bite the bullet and replace it but would still like some cooling until it can be replaced...

    Any ideas?

    Thanks.
     
  2. agmantoo

    agmantoo agmantoo Supporter

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    Clogged air filter and low freon are two reasons.
     

  3. oz in SC

    oz in SC Well-Known Member

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    It is a package unit(about the size of a house :haha: ) and I removed the air filter and it DOES need replacing...wherever the replacements ARE..

    It may be low on freon although WHY it suddenly decided to stop working is a mystery..perhaps it is simply wanting to die... :D

    Is it possible to charge it yourself or do I need to pay $$$ to one of the many HVAC companies to do it?

    We REALLY hate to have to spend $5,000-$6,000 on a new unit but it WILL help sell the house I guess....

    It will of course add value to the house I suppose.
     
  4. Jack in VA

    Jack in VA Well-Known Member

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    If it's that old, it probably has a belt on the blower.Check it.Or the coils are dirty. And, no, you can't add your own Freon. It's illegal.
     
  5. oz in SC

    oz in SC Well-Known Member

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    Well it is running right now and cooling slowly.

    We will most likely buy a new unit.

    Thanks.
     
  6. Darren

    Darren Still an :censored:

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    My mother has a central A/C unit that's close to 50 years old. Several years ago I had to locate a tank of freon to recharge it. I think it's R500. I lucked out and found a full tank for way less than the $1,000 quoted. The company would have liked to replace the unit but when I asked the tech how long it would last, he said probably forever with maintenance. Needless to say the antique is still working. The compressor looks like something out of a Jules Verne story and is belt driven by a separate motor. It's the original compressor.

    I asked the tech how long the new units would last. He said maybe 7 or 8 years if you were lucky. Some of the old stuff will outlast you if you take care of it. The service company we use handles commercial and industrial HVAC as well as residential. I think in some cases, they do a better job than the folks that just do residential work especially with old stuff.
     
  7. oz in SC

    oz in SC Well-Known Member

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    If we weren't planning to sell we would just have it looked at BUT as it is,it is a major eyesore and potential sticking point to selling.
     
  8. 2story

    2story Well-Known Member

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    pay me now or pay me later
     
  9. Runners

    Runners A real Quack!

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    It could be:

    a. Stuck expansion valve
    b. partially plugged capillary tubing
    c. moisture in the system (causing freezing @ cap tube/expansion valve)
    d. a LEAK - resulting in low refridgerant
    e. low air flow over the evaporator (plugged filter, faulty fan motor)

    Did the service person install / replace the filter dryer when the compressor was installed? If not, it could be a-b-c-e, take your pick, it's easy to fix if you got the torch, line tap, pump & R22... just some TIME involved.

    Whatever the case, icing in the evaporator (the coil part in the furnace) is responsible for many an unecessary but expensive service call - that often times could have been solved by the home owner. Before anyone can really work on it, the evaporator needs to be completely thawed - turn the AC off and run the furnace fan until air flows fast and freely through it, or out the vents for a hour. When the water stops flowing out of the drain tube @ the furnace, then you can start troubleshooting. I said that to save you some time, 'cause the service man is usually paid by the hour, not the job.

    As someone already said, make sure your furnace filter is OK, belts OK (if you have them), and everything looks nice a clean.

    (I started to write what to listen for @ the evaporator, but can't figure out how to write it in a way that's easy to understand - hiss, bubbling & spraying water sounds. Same goes for watching the evaporator as it begins to ice up, if it all gets cold, part or just by the expansion/cap tubing.)


    In short, you can usually troubleshoot this in just a couple of minutes with simple cleaning and/or a manifold gauge set - before you shoot a bundle of $$$.
    If it needs some R22, trust me, there's LOTS of it out there (just like there is lots of R12 & R502). They just don't make it in the USA - and even if you get socked for $100 in R22 & a service call, it's still cheaper to fix a leak, add a filter /dryer and recharge.

    Legalities.... sigh! When we were kids with BB guns, we shot every bird in sight. Once a neighbor said, "you can't shoot that Robin, it's protected!" I guess it forgot it's BB proof vest that day... the cat ate all the evidence.