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  1. #1

    Compressor diagnostics...

    As I mentioned in my introduction, I consider myself a meatball surgeon who wants to go from "Just keep 'em running" to a more service tech line of thought i.e. fix the problem not just patch it.

    Yes I'm Type 3 certified and, yes I've been doing this for going on 10 years but, in the end, my real servicing experience would probably make a first year journeyman giggle. The property I learned on was over 15 years old so, when a unit died, the rule was simply replace it with a new one, then scrap out the old. I did over 40 change outs on that property in that manner.

    The problem is that now I'm on a relatively new property and have been here almost 7 years. Service has been pretty much limited to capacitors, fan boards, the occasional leaking coil and a squirt of R22 here and there. I've changed out 5 units here, primarily from hurricane damage. My hardest challenge was finding the shorts that would blow the 5 amp fuses on my Carrier fan boards (wires rubbing inside the condenser would wear thru, shorting against the cabinet).

    I now face my first possible compressor failure, something I've never learned to diagnose before. Because the units are around 8-9 years old, I don't want to unjustly send it to an early grave without properly evaluating whether the compressor is truly dead. Could someone walk me through the basics? I'd really appreciate it.
    (The wise men of modern thought) adore a god made of putty or of wax - plastic, effeminate, molluscous, with no masculine faculty about him, and no quality that entitles him to the respect of just and honest men, for a being who cannot be angry at wrongdoing is destitute of one of the essential virtues, and a moral Ruler who is not angry with the wicked, and who refuses to punish crime, is not divine. ---Spurgeon

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,855
    Well, without getting TOO technical in an open forum, there are 2 types of failures, electrical and mechanical.

    Mechanical is usually pretty simple to diagnose. Motor is running, but it isn't pumping. Often, this is accompanied by really bad noises from inside due to damage.

    Electrical failures are a bit more difficult.

    First, the types must be divided.
    Open winding, shorted winding, grounded winding.

    Types #1 and #3 are usually pretty easy to diagnose if you know your way around a meter.
    #2 requires knowing how the motor is wound and the correct resistance readings for the windings. This info can be obtained from the manufacturer.

    The only other type of failure is a "locked rotor" This lumps in technically with mechanical failures, but I am addressing it separately, because most compressors are incorrectly diagnosed as being "locked up" when the problem is actually in the starting components.

    If you do not understand a single phase starting system, then learn about potential and current relays, how they are wired and how they work.

    Whenever I am unsure, I try new start components before condemning a compressor.

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,556
    Sorr.
    Walking you through the check out.
    Would by step by step instructions.
    They are not allowed in the open forums.

    You have enough post, so apply for pro membership.

    Then you can ask questions in the pro tech forum and get real answers.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  4. #4
    Thanks guys, I have my application in for Pro membership pending, worse comes to worse, my plan is to simply swap out with another unit on the property from an undesirable apartment (things are scary slow in the industry right now) I tried a hard start and that didn't do anything.

    I'm getting better with my meter usage, my biggest problem is that I have so many other things I handle in my job between plumbing, carpentry and electrical that I have a booger of a time knuckling down the basics of HVAC repair---I simply don't do it often enough to lock it in my gourd. I understand about the step by step issue...really wouldn't want this forum to wind up in a Bob Goldwater commercial...

    "This is serious, if you or a loved one have frost bitten your fingers, got a jolly tingle from a capacitor or sliced and diced your knuckles on a coil because of advice given by that snorkel nosed lizard thingie on HVAC-Talk, you may be eligible for a large cash award."
    (The wise men of modern thought) adore a god made of putty or of wax - plastic, effeminate, molluscous, with no masculine faculty about him, and no quality that entitles him to the respect of just and honest men, for a being who cannot be angry at wrongdoing is destitute of one of the essential virtues, and a moral Ruler who is not angry with the wicked, and who refuses to punish crime, is not divine. ---Spurgeon

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