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Air Conditioner Repair

Discussion in 'Electronic Repair' started by Chris F., May 21, 2004.

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  1. Chris F.

    Chris F. Guest

    I could almost swear that in an early version of the RepairFAQ (about 8
    years ago) there was a sizeable FAQ on repair and troubleshooting of air
    conditioners. Such an FAQ is nowhere to be found on the current RepairFAQ
    site. Have eight years of time fogged up my memory, or did Sam G. pull that
    FAQ for some reason?
    Anyway, here is the problem I was hoping to get some advice on. I recently
    picked up an old air conditioner in someones trash (I don't have the money
    to buy a new one). I thought maybe I could tinker with it and get it going.
    When I got it home and plugged it in, the fan worked great but as soon as
    power was applied to the compressor motor (turn up the COOL setting), the
    lights would dim WAY down and I'd have to turn it off immediately (otherwise
    a circuit breaker would blow). Once inside the unit (where I found the mfr
    date of Oct. 1975!), I disconnected the fan motor so I could hear what was
    going on in the compressor. Sure enough, it would just hum and dim the
    lights. At this point I figured it was shorted and that the unit was junk,
    but for some reason I kept cycling the power on and off to see what would
    happen. After several tries, the compressor loudly roared to life and the
    shop lights were no longer dimming. It was obvious from the noise, that the
    compressor has a very hard time starting up (seizing?). And it appears that
    the unit is sealed, so there's no way to service it (also, I don't want to
    fool around with the freon). My plan of action for now is to install a
    separate switch for the fan, so I can leave it off and listen for the
    compressor to start. Obviously this would be a bit of a nuisance, but it's
    still preferable to sweating my brains out in the 40oC summer heat!
    Anything else I can try, or is this the best I can hope for?
     
  2. Bob Urz

    Bob Urz Guest

    If your lucky, the start capacitor is bad on the compressor.
    Looked for a metal canned cap connected to it and replace it
    and see what happens.

    Bob
     
  3. Jerry G.

    Jerry G. Guest

    It sounds like the start capacitor on the compressor has to be changed. If
    this is not the fix, the compressor will have to be changed.

    --

    Jerry G.
    =====


    I could almost swear that in an early version of the RepairFAQ (about 8
    years ago) there was a sizeable FAQ on repair and troubleshooting of air
    conditioners. Such an FAQ is nowhere to be found on the current RepairFAQ
    site. Have eight years of time fogged up my memory, or did Sam G. pull that
    FAQ for some reason?
    Anyway, here is the problem I was hoping to get some advice on. I recently
    picked up an old air conditioner in someones trash (I don't have the money
    to buy a new one). I thought maybe I could tinker with it and get it going.
    When I got it home and plugged it in, the fan worked great but as soon as
    power was applied to the compressor motor (turn up the COOL setting), the
    lights would dim WAY down and I'd have to turn it off immediately (otherwise
    a circuit breaker would blow). Once inside the unit (where I found the mfr
    date of Oct. 1975!), I disconnected the fan motor so I could hear what was
    going on in the compressor. Sure enough, it would just hum and dim the
    lights. At this point I figured it was shorted and that the unit was junk,
    but for some reason I kept cycling the power on and off to see what would
    happen. After several tries, the compressor loudly roared to life and the
    shop lights were no longer dimming. It was obvious from the noise, that the
    compressor has a very hard time starting up (seizing?). And it appears that
    the unit is sealed, so there's no way to service it (also, I don't want to
    fool around with the freon). My plan of action for now is to install a
    separate switch for the fan, so I can leave it off and listen for the
    compressor to start. Obviously this would be a bit of a nuisance, but it's
    still preferable to sweating my brains out in the 40oC summer heat!
    Anything else I can try, or is this the best I can hope for?
     
  4. Cyrus

    Cyrus Guest

  5. Chris F.

    Chris F. Guest

    This was something I had considered, but the cap tested good for
    capacitance (15uF @ 350VAC). However, as you guys have informed me, it may
    be breaking down under load. I will try replacing it (probably with 4 or 5x
    3.5uF/350VAC caps, since I don't have anything that big) and see what
    happens.
    As I replied to Jerry in an Email, the compressor started up fine when I
    tried it this morning (several times), and the only difference was that the
    shop area was much colder than yesterday. Seems to further suggest a bad
    cap, as cold would only make sticky lubricants in the comp motor seize that
    much worse.
    Thanks for the advice.
     
  6. There is probably some info in the Small Appliance Repair FAQ
    but nothing as extensive as you recall. There are several
    good large appliance repair sites so what's the point in
    duplication. :)

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
  7. KLM

    KLM Guest


    You are right about the system being sealed and not home-serviceable.
    Since the compressor sounds normal (no clunking) and it does cool one
    can assume that the problem lies elsewhere. Look at the switch relay
    attached to the compressor canister. Try cleaning that first. The
    next step may be to replace that relay. If not bypass the relay and
    switch it on and off manually as suggested by yourself. Also clean
    all the insides of the a/c cabinetry, Your fan solution may work.
    Beyond that I don't suppose its worth spending anymore time or money
    on it.

    If you cut off the three tubes to the compressor (leave a few inches
    for a pressure regulator, etc.), you have an air brush silent air
    compressor that is worth a few hundred bucks (as prettied up by
    vendors) to hobbyists. You can probably ask for a hundred or so and
    all you have to do is to clean it up an give it a coat of paint. The
    law about releasing Freon applies only to businesses that deal with
    refrigerants. It does not apply to private individuals. If you are
    still concerned with the environment bring your a/c to a car aircon or
    some aircon business. They will be quite glad to remove that for you
    and resell the Freon for old equipment service calls.

    When salvaging the compressor always work with it in an upright
    position else the oil will leak out. Furthermore the compressor may
    pop out of its mounting springs and that's unrepairable.
     
  8. jakdedert

    jakdedert Guest

    The compressor is not the issue...the circulating fan is.
    Home units use a different refrigerant than car a/c. The freon would be
    worthless to an auto a/c shop, and probably would contaminate their
    equipment. I've heard that the oil coolant in a/c compressors make them
    worthless for painting purposes, as it contaminates the paint.

    jak
     
  9. Guest

    A bad relay wouldn't draw excessive power. I agree that the starting
    cap is probably bad.
    The original post said it was the compressor

    I'm pretty sure the law applies to individuals.
    My window ac unit and my cars use R134a. They may use different oil
    types though. Older cars still use R12.

    Huh?
     
  10. A bad relay wouldn't draw excessive power. I agree that the starting
    Sounds like the Cap is going to be the first thing that you should replace.
    I have run into that type of problem all the time.

    It does.
     
  11. Bob Urz

    Bob Urz Guest

    Most sealed A/C compressor use the oil in the refrigerant stream for
    cooling. There NOT like a air compressor with a oil sump.
    It would probably burn up from lack of lubrication if you used it
    long for air compression. Even may refrigerant recovery units state
    do not use with virgin refrigerant with no oil in it for this reason.


    The
    A Window unit is usually a sealed unit with no service ports on it.
    Does not make it easy to recover the gas. I doubt that anyone would take
    R134 without charging you for a disposal fee. Commercial recovered gas
    is suppose to be sent back to a EPA listed recycler. CHeck out the EPA
    web site under 608 and 609 to find out more


    Bob
     
  12. jakdedert

    jakdedert Guest

    But older AC-powered units used something else...don't remember just exactly
    what at the moment; but it was not compatible with R-12. R-134 is so cheap
    as to not be economically recoverable in cases like this...and
    environmentally more friendly when vented to the atmosphere anyway.

    That's why it exists.
    I don't understand that one either, but the other poster must....

    jak
     
  13. Actually, the cool Freon from the evaporator is used for cooling.
    The oil is used for lubrication.

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
  14. Guest

    Possibly R-22 or R-502 for fairly old units. I doubt an a/c shop
    would even try to recover the freon without being damn sure of what it
    is. He doesn't want to contaminate his equipment.
     
  15. KLM

    KLM Guest


    I don't know about car a/cs but I had salvaged several fridge
    compressors and they all work fine as air compressors. I would have
    obtained a lot more from the recycling dump except there is a law
    against taking anything from the recycling dump. At this recycling
    dump I happened to meet a guy from a fridge business who has a
    contract (ie. permit) to remove the refrigerant from the dumped
    fridges. He drains them into a flexible bag. Its a win win situation
    where he gets free refrigerant and the city gets to comply with its
    own environmental laws.

    The city recycling center is a place where you can dump electronics
    waste, small and large appliances and harzardous materials. The
    harzardous materials are mostly paints and solvents. If you need
    paint and are not too fussy about color, you can pick that up for free
    from this dump. This dump is a fascinating place and I am amazed at
    the really good stuff that gets thrown away: good looking stereo
    sets, TVs, fully populated late model PCs, monitors, printers,
    microwave ovens, etc. darn, I wish they would let me take them for I
    think most of them need only minimal repairs to make them whole. This
    recycling dump called the EcoCentre is my city's way of dealing with
    hard to remove or harzardous household waste. Its within the city
    limits and easily accessible. I think it a great idea because the
    center gives a place for us to get rid of appliances like fridges, TVs
    and all the stuff that the garbage man wouldn't lift and stuff
    (solvents, paints, etc.) that should not be dumped raw into the
    regular dump. That way people won't be tempted to dump their stuff
    into the farmers fields or some vacant land.
     
  16. jakdedert

    jakdedert Guest

    They work as air compressors, but have you tried painting with them? I've
    seen those coolant recovery kits (somewhere). That's a great solution. I
    wonder if you could get a similar permit to salvage other things?
    I know what you mean. Dumpster diving is one of my (and I'd venture to say
    that I'm not unique among the posters in this group) favorite pastimes.

    jak
     
  17. Hi!
    I thought some did use R-12 and others used 22a...but maybe my memory is
    wrong.

    In any case, I've also seen an R500 or somesuch kind of refrigerant. I have
    two fairly new Magic Chef dehumidifiers that use it...with notes on the
    compressor stating that it can be used with the 500 stuff or R12 IIRC.
    If it's R22, wouldn't it be useful to someone in the HVAC industry...don't
    those people reclaim old freons and such???
    I had a friend of mine turn an old compressor into a solder sucker of sorts.
    It seems to work quite well for this purpose.

    William
     
  18. KLM

    KLM Guest

    The guys at the Eco-Dump were not encouraging. That begs the
    question. Since the stuff is sorted and supposedly have a value more
    than just ordinary garbage or as scrap metal I do wonder if they
    dismantle the stuff to salvage value parts?
    ---------------------------------------------------------------------------------

    I'll use this opportunity to answer a number of questions on silent
    compressors.

    I lucked into a Art Store supplies air compressor at a bankruptcy
    sale. It was in peices but the compressor itself looks whole, $50
    for something that cost $650 in the catalog. After reassembly it was
    spitting out oil somewhere and I fixed that by making a new gasket for
    the seal between the canister lid and the canister. The canister top
    was removeable to form the lid. In fridge compressors this is welded
    shut. They call this a hermetic compressor in the trade.

    On an unrelated occasion the shop fridge gave up the ghost and I
    salvaged the compressor which didn't work. So I cut open the sealed
    cannister to look at the insides. It was the same as my airbrush
    silent compressor.

    The compressor base had a rectangular base with rubber grommets on
    each corner. These grommets were friction fit into four coil spings
    that were welded to the canister base. The function is to isolate the
    compressor vibration. In the fridge compressor one of the grommets
    had popped out of the spring. Every time the compressor started or
    stopped the imbalance caused it to clunk against the canister side.
    The electrical cable flexed enough times to fracture, caused a short
    and fried the motor. That's why you should always transport fridges,
    a/cs and such equipment upright.

    If you look at the Paasche 2000 at <
    http://www.airbrushheadquarters.com/compressors/compressors-paasche.htmlyou will recognize the compressor canister behind the compressor tank.
    The rest is just furniture that different manufacturers redesign to
    look nice and look different. If airbrush silent compressors cost as
    much as a fridge you should see the same thing set up as a dental
    compressor. An example of a low end dental compressor is at <
    http://www.idsdental.com/dencom.html >

    Since my art shop compressor lid can be left uncovered I could see
    what worked. The compressor itself is a simple single banger. Its
    crankshaft is extended to form the electric motor shaft. This is
    aligned vertically so that the motor commutator dips into the oil
    reservoir. When the motor runs the oil is drawn through the
    motor-crankshaft and spins up and out through the top like a garden
    sprinkler.

    Neat. The oil therefore has three functions. As a lubricant, as a
    solvent for the refrigerant and as a coolant. The solvent function is
    similar to the role of acetone in an acetylene bottle. More gas can
    be stored with a solvent present than can be liquefied by compression
    alone. The coolant function is explained thus. As the oil passes
    through the motor-crankshaft it absorbs the heat of compression. When
    spun out at the top the oil hits the canister side and drips down back
    into the reservoir. In the process the canister wall cools the oil.

    To salvage a fridge compressor to use for painting just keep running
    it until the dissolved refridgerant is outgassed. Add a pressure
    regulator that has an oil filter.
     
  19. LanceBro

    LanceBro Guest

    if the unit is 120 volts...sometimes when a
    window unit is stored the compressor can lock...an old trick is to hit the
    leads of the compressor with 220 so that's 110 to each leg of the compressor
    quickly and this will unlock the compressor....this is done after you have
    checked the windings and made sure you do not have a short in the compressor
    and that the starting cap is fine and your thremal overload is working...
    remember this is done when you think all is fine but the compressor is
    definitly yourt problem.....
    beleive it or not this does work.....

    most window units are r22 old ones you may findf some real old 12's but few
    and far between.....

    all new ones are 134
     
  20. I would NOT recommend this as an option for anyone who isn't very experienced
    and knowledgeable enough to have rule out other causes. It's very easy to
    ruin the compressor entirely performing such stunts.

    --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: The email address in this message header may no longer work. To
    contact me, please use the feedback form on the S.E.R FAQ Web sites.
     
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