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  1. #1
    Join Date
    Feb 2008
    Posts
    13

    AC Compressor Contactor Voltage Issue

    I have a 141,000 BTU Pool Heat Pump based on a Trane compressor, and it recently blew its transformer.

    The AC tech came out and said "It would be $500 to replace it, but we don't have a 24v/12v transformer, so I can't guarantee we can do it."

    Left high-and-dry, I researched it on my own... I replaced the original dual-tap transformer (12v/24v) that was a 40VAC with the only dual-tap I could find, a 96VAC unit: Steveco 90-T96F2 here: http://www.drillspot.com/products/12...ol_Transformer

    ...After replacing the transformer myself, verifying that the electronics work again, I contacted the AC guy to come back out. I never received a return call after two weeks of trying, so I was on to my second AC guy...

    The next AC guy told me that there was no voltage at the COMPRESSOR CONTACTOR and that the entire circuit board would need to be replaced. He did not want to spend more than 5 minutes with it, so he charged me a 1.5 hour fee, for 10 minutes of "review", and left.

    After a second time of being left without a solution, despite paying for one, I decided I would take a look on my own. Here is what I found:

    Everything works fine if I push-in the COMPRESSOR CONTACTOR, so I am sure it's just a matter of getting voltage to the contactor. When I test the voltage @ the contactor, while it's connected, I get nothing. If I disconnect the leads from the contactor, they are providing about 21V.

    Not being a professional HVAC person, I'm stumped and out of my league:

    (1) How could the Heat Pump's control panel be supplying voltage successfully, but when connected to the CONTACTOR, I do not register any voltage? Could it be that the one leg of the wire feeding the contactor is shorted in the contactor?
    (2) Why is the voltage being supplied to the contactor, only 21v? When I test the transformer's 24V leg, it's putting out about 28v. Does the contactor need a full 24v to switch? Does this sound like it could be the source of my problem?
    (3) What is my best "Next Step"? Should I just buy a new contactor and try replacing it, or should I try to trace down something else?

    This is not my bag and I'm doing the best I can because I'm afraid to spend more money for a guy that just charges me money and leaves. I desperately need a "next step" -- any feedback you can provide would be greatly appreciated, or if you are in South Florida and you feel you would like to service the unit, please let me know.

    Thank you in advance,
    RKM in WPB, FL

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,808
    Sorry. But site rules forbid us from giving you DIY advise on how to fix it.

    But, I doubt its the contactor itself.

    Go on line to the manufacturers site. And find a dealer. They should be able to take care of your problem.
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  3. #3
    Join Date
    Feb 2007
    Location
    18951
    Posts
    1,593
    I'd really like to know the other side of this story. Can you get those contractors to come on here and explain their version of what happened.

  4. #4
    Join Date
    Feb 2008
    Posts
    13
    TO BEENTHERE: The company that makes the Heat Pump is "FAFCO" and they are out-of-business, so I cannot get a list of distributors or autorized repair companies, or any of the proprietary components (which is limitd to the controller board, everything else appears to be off-the-shelf stuff).

    I found this site because another DIY person asked a similar question and you did answer him, so I hoped you might be able to provide me with the same courtesy. That post was at: http://hvac-talk.com/vbb/showthread.php?t=139939

    TO BOBB25: I'm a bit taken back and perhaps sorry for posting. There really is no back-story, and I'm certainly not complaining about the contractors, it's just that if you try something twice and you don't get anywhere, maybe it's easiest to take it into my own hands. If you are more concerned with the story than with the problem, I'll be happy to provide you more information, and offline, I'll give you their phone numbers if it's of major concern:

    First contractor: aAA Air Conditioning in West Palm. They came out, said the transformer is blown and they can't check anything else until they replace it. They said it would be $500, but that they could not guarantee they would be able to find a 24V/12V dual-tap transformer, asked me for payment, and left. I called him two months later, after I found and installed the 24v/12v transformer and he said he remembered me and that he'd be out within the next two days. I did not hear back after two days, so I called him and did not receive a return call. I called the following day again without a return call (and so on, every other day for a spell).

    Second contractor: A friend of a friend was referred to me, I'm not even sure of his company name -- he mostly just charges refrigerant -- does not get into the circuit boards, etc. He was nice enough to come out quickly but was not able to do anything, as I stated. He said "your compressor is not coming on -- that probably isn't something I can fix. let me take a look at your safety relays and make sure they are not the problem ... nope those are not the problem, but it looks like you're not getting voltage at the contactor, which means the circuit board needs to be replaced, and that's not something I can do." then he charged me the money and left.

    So... I'm not sure what more of a "story" you want, but there really is nothing more to the situation and I'm simply looking for advice so I can get to the root of the problem. By all means, if you are in South Florida, come out and take a look for yourself -- I'm more than happy to pay for someone to work on the unit, if you think it's something you're familiar with, which was not the case with my original two contractors, it seems.

  5. #5
    Join Date
    Feb 2008
    Posts
    13
    BEENTHERE: Based on your suggestion that it was not the connector, I tested by wiring directly from the transformer to the connector, giving it the roughly 28v directly off the transformer, and it switched fine.

    Therefore, it seems the lack of voltage (21v being provided) is the problem. Since it's against the rules to give me specifics on fixing it, could you just give me your basic opinion on whether it's most likely the controller board, because if so, I'm probably not going to find anyone that can fix this, being that the company, FAFCO is out of business. If it's that something else is sucking down voltage (which I cannot think of anything else powered by the transformer), then maybe it's not the proprietary controller and there is hope.

    Thank you in advance.

  6. #6
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,409
    My advice is to ask friends and family who they have used. If this cannot be done. Call an HVAC company. Explain to them your situation and frustration over the first 2 companies and that you would like to get it fixed. Tell them the type of equipment. Hopefully that will weed through the hacks.

  7. #7
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    any electrician, especially one familiar with industrial controls, should be able to fix --
    they will know where to get transformers,
    & about voltage requirements for contactors.
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  8. #8
    Join Date
    Feb 2008
    Posts
    13
    Using the advice earlier in the thread, I went to another heatpump company (Hayward) and look at their authorized resellers -- most of them are pool companies, which is not a good idea, so I found the few that are more HVAC related.

    I called three companies (each because it seemed like the prior did not really know, and was just saying 'we can do it' to anything I said), however, they all gave me the same blanket answer 'that is no problem.' to which I would say 'okay, but it may be on the controller board and this is a discontinued product' ... in each case: 'it's not a problem.'

    So ... I don't know whether I just got really un-lucky the first two times ... or ... I'm about to be unlucky a third. But since I'm prohibited from receiving technical feedback here, I'll try the process one more time and see what happens.

  9. #9
    Join Date
    Feb 2008
    Posts
    13
    cem-bsee -- thank you for the reply, that is extremely helpful information.

    Any idea how to separate electricians who know industrial controls?

    I did a search in the Internet YP, but no separate section for this and it's not mentioned in anyone's advertisement. Should I just call each and say "do you specialize in industrial controls?" -- I am concerned with doing this based on my last endeavor where I get a blanket 'oh yes, of course' from everyone!

  10. #10
    Join Date
    Feb 2008
    Posts
    13
    So I took your advice and one of the companies I had contacted, Polar Bear here in West Palm, said it would be no problem. As soon as the tech arrived, he said that the lady on the phone did not tell him what I said and that it might not be something he can do.

    He tested everything and noticed the full 28v on the line that goes to the connector; which registers zero volts when connected to the connector, and he said that the problem was that it was "micro voltage" -- that there was voltage but no amperage getting through. He explained that the problem is definitely in the control board and that there is no HVAC company would be able to fix it.

    Because he felt bad that the woman did not listen to me, and that I had told them in advance, he did not charge me the service call. It was a real treat to deal with such a great company, I will surely use them for other HVAC in the future.

    Unfortunately I'm back where I started. Since no HVAC company can fix this issue, and I don't know how to find the proper type of electrician, I'm stuck trying to find an old 24v relay board I can connect on my own or something along those lines.

    All I need is something to deal with 3 sensors: flow, high/low pressure switches ... then trigger the fan/compressor relay -- unless I'm missing something. I don't need the thermostat feature, which is the only complex component. So I thought that I'd try to find something like that, or just try to build my own, being that it's fairly straightforward.

  11. #11
    Join Date
    Feb 2005
    Location
    GEORGIA
    Posts
    1,532
    I just googled "FAFCO".............

    First hit was a very nice web site.

    They seem very alive and well.

    Are ya sure you tried em?

    "Value our Differences"

  12. #12
    Join Date
    Feb 2008
    Posts
    13
    Yes, I'm sure. Trust me when I say it would have been much easier to just call them, than to post here and get beat up about it.

    You'll notice on their website they only sell solar and home water heaters. This heat pump "division" was in Florida, and an entirely separate company. Apparantly they just licensed the name from the much larger FAFCO in California. They also went by the name "Peregrine Industries" (you'll find some companies under that name too, just saving you the time of searching) but this Peregrine Industries/FAFCO was a Florida company which is now defunct.

    The company in California won't even talk to me. I've tried to call them on three or four different occasions, to try and get a different answer or someone that will say something beyond "we have no idea, sorry." It takes about 10 calls just to get through to a person.

    So I've been calling around to find a "universal" control board. That does not appear to be an option, so I may be stuck having to throw some relays together.

  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,808
    Its possible. You might find an electronics shop that can repair the board.
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