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Lennox Central AC Condenser Unit still trips 30 Amp Breaker after Cleaning Condeser and Evaperator?

Post in 'DIY and General non-hearth advice' started by Don2222, Aug 16, 2012.

  1. Don2222

    Don2222 Minister of Fire

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    Hello

    Well now it is about time to get the bloody unit working!

    I cleaned the Condeser Coils with the foam cleaner and hosed it off.
    Also replaced starting capacitor and 30 amp panel breaker in main breaker panel inside house.
    See detail and pics in link below.
    http://www.hearth.com/talk/threads/...r-buzzing-after-the-coil-cleaning-help.88931/

    I cleaned the Evaporator A Coil with the Evaporator cleaner that does not need rinsing
    Also vacuumed the return air filter and vacuumed out the Evaporator and fan housing.
    See detail and pics in link below.
    http://www.hearth.com/talk/threads/...coil-cleaning-and-orientation-question.88982/

    I also patched up duct leaks in the attic with foil tape!

    The next step if to get a new Contactor!

    So here are my 3 questions to you AC experts? ? ?

    1. Will a new contactor solve the problem of the 30 Amp breaker tripping?
    If not is it a compressor going bad?

    2. Will 5 more amps of contactor relay load capacity help?

    3. Since the old contactor is a single pole does that mean there is a heater in the compressor that is powered on when the compressor is not running to warm the R22?

    The old one was single pole with 24 VAC coil
    3100-150179

    Voltage___FLA__LRA
    240/277___25___150
    ______________________________________________________________________________
    The new one I got is 2 pole 24 VAC coil and is better because it is more enclosed.
    I only need one pole so If I hook up 1 pole and it wears out then I can use the other pole. It will last twice as long!
    They did not have a 25 FLA so I got the 30 FLA with specs shown below:
    Voltage___FLA___LRA
    240/277___30____160

    Pic 1 shows old contactor exposed coil - see yellow arrow
    Pic 2 shows old contactor shunt - see yellow arrow

    Pic 3 shows wires connected to the new contactor the same as the old contactor
    However to use this double pole as a single pole the 2 black wires at the top were removed and pushed onto the bottom clips next to the black incoming hot lead. See Green Arrows in pic.

    So I did change the black leads to the bottom terminals, then started up and AC is still running.
    It has only been about 3-4 hours so far!

    Attached Files:

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  2. heat seeker

    heat seeker Minister of Fire

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    I don't think replacing the contactor will solve your problem.

    The load capacity only states how much current the contacts can handle.

    Can't help you about the heater, although some units do have heaters in them.

    It's possible that the breaker has been damaged due to the previous problems you had. Do you have another one you can swap in? Or can you measure the actual current being used in each leg?
  3. woodgeek

    woodgeek Minister of Fire

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    Not an expert but I tinker with mine a fair amount....

    I agree with heatseeker....

    How old is the unit??
    I don't think an AC would have a heater....while a HP might.

    A random thought....I was wondering if you had short cycled the compressor during your testing. If you don't give the compressor at least 5 minutes after stopping before you restart, it can be potentially be damaged or have a harder time starting. IOW, you would find that the compressor went to a 'buzzing' state, but then >5 minutes later it would start up fine. On the same note, does your thermostat have a 5 minute cycle protection built-in (and activated)?
    heat seeker likes this.
  4. basod

    basod Minister of Fire

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    Larger crankcase compressors will have heaters in them - typically industrial units.
    You need to ohm out both the compressor and fan leads to ground, during cleaning I've seen more than a few fan motors insulation compromised by getting the cleaner in the windings. Phase-phase short will pop a 30amp breaker. Same could be true of the motor lead connections - check under the weather cover on the compressor for arcing(if it is removeable)
    Disconnect the fan wires off the contactor and see if compressor runs without tripping breaker. Then remove the compressor leads and reconnect fan leads, one or the other will trip it. Just to be sure no other wires are grounded lift both of them and depress the contactor which would eliminate any issue with carbon tracking in the contactor being your issue.
  5. begreen

    begreen Mooderator Staff Member

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    Replace the breaker and examine all connection for tightness including wirenut splices in between the panel and the unit. Also assert that the wire gauge is correct for the load and length of run.
  6. Don2222

    Don2222 Minister of Fire

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    The current draw on each leg is 15 amps for the compressor and the fan. After the 30 amp breaker was replaced it started tripping more not less! After the contactor was replaced it did not trip much at all!

    However I believe it still may trip on a very hot day!

    So before I ohm out the Compressor we should try a "Hard Start Kit" :) Why didn't someone mention this?
    http://www.grainger.com/Grainger/SUPCO-Hard-Start-Kit-4E240
  7. Don2222

    Don2222 Minister of Fire

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    The T-Stat is an old round unit that has heating or cooling and worked fine for 10 years! You are correct, because the unit is about 10 years or more old it does not have a heater band around it. Still no sense in switching both legs if you do not have to.

    So before I ohm out the Compressor we should try a "Hard Start Kit" :) Noone mention this?
    http://www.grainger.com/Grainger/SUPCO-Hard-Start-Kit-4E240

    I still can bump up the breaker to 40 amps. However I will try the hard start kit first.
  8. boosted3g

    boosted3g Feeling the Heat

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    A hard start kit is usually installed as a band aid or a hold over until the repair can be properly made. Think of it as a super capacitor. I replied in your other thread and I missed some info that was pertinant in other threads on the same topic. If all this happened after a cleaning I would start with what was said at the beginning of this thread.
  9. Don2222

    Don2222 Minister of Fire

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    Hi boosted3g
    It did not happen after cleaning.

    The breaker started tripping, that is what caused this whole issue.

    So we analyzed the system. We put the breaker back on after it tripped and measured the current of 15 amps in each leg. The FLA is 17 amps. It was running ok when we initially saw the system. The customer stated it kept tripping the breaker when it was hot out. The fan above the compressor was not blowing as much air as it should so I cleaning was clearly needed and should be the 1st step of the repair. So I cleaned the compressor coils and the next day, I also cleaned the evaporator A coil and changed the 30 amp breaker and 25/5 MFD capacitor on the outside condenser. It was tripping more with the new breaker so I changed the contactor and we got it running pretty well again. I think it still may trip in a real hot day so a "hard start kit" may be an inexpensive way to get it working the rest of the summer?
    A new compressor is $1200 bucks min?
  10. woodgeek

    woodgeek Minister of Fire

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    My brand new HP had the occasional aborted start (noticed b/c it browned out my lights for a few seconds). Never tripped a breaker, and resolved on its own on later cycles. (My house has a rather puny aerial line to the street, but the utility owns it, and says its aok).

    I **think** the nominal starting amps on these things is close to 100A peak, and that most breakers are designed to ignore starting pulses. I think all compressors have the occasional rough start. I imagine as the units age those rough starts become more frequent?

    I had a hard-start kit installed on my HP just to reduce the light flicker in my house. It is not clear that it has done anything else for me. The band-aid comment above sounds about right to me. FYI...there are third party starter kits out there on the intertubes that should be avoided. Go with a manufacturer-listed part if you try this route. IIRC three wire units are ok, two wires are junk??

    Anyhoo...how do you know the tstat is not limiting the contactor switching current?? E.g. from oxidized contacts?
  11. Don2222

    Don2222 Minister of Fire

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    Hello

    My heating man says he has seen alot of Hard start kits installed to prevent light dimming same as in your case. So it is not always just a band aid fix. They do have many more harder starts just before the compressor fails, but having a hard start kit is a good cushion to prevent your own power surging! Good to know they come in two and three wire kits. Thanks, I will check if I need one.

    Please tell me what is the Breaker Amperage that your AC is connected to? My neighbor has a 30 amp and my AC man thought it should be 40 amp for this AC Compressor.

    These hard start kits really save on your compressor wear!
    http://www.amazon.com/Compressor-Saver-Hard-Start-Capacitor/dp/B003FNMADE

    Product Description

    Starting up is the hardest time in the life of any type of electrical equipment. Ever notice that light bulbs almost always burn out when you first turn them on and not while they are on? This is due to the huge current that rushes in when a switch is thrown and power is first applied. Your air conditioner uses anywhere from 5 to 10 times more power on start-up than it does while running. With this burst of power comes a surge of heat that accompanies the electrical current. This heat damages the compressor, the terminals, the windings and run capacitor - all vital components of your air conditioner. The 5-2-1 Compressor Saver® protects these components by significantly reducing the amount of time it takes for your compressor to start - in some cases up to 50%. This means your air conditioner and compressor will bear ½ the stress, strain and heat each and every time it starts. Considering that your air conditioner may start up more than 6,000 times in a single cooling season, the positive impact that the 5-2-1 Compressor Saver® has on your air conditioner is significant. Before you replace your air conditioner, try adding a 5-2-1 Compressor Saver®. The 5-2-1 Compressor Saver® might save you from having to outlay thousands of dollars to buy a new air conditioner or compressor. At a fraction of the cost, installing the 5-2-1 Compressor Saver® is a wise investment.
  12. woodgeek

    woodgeek Minister of Fire

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    My 4 ton HP unit pulls ~26A running, and wants a 40A breaker and wiring. For the smaller system you are working on pulling 17 A IIRC, a 30A breaker seems like the right size.

    The proper answer comes from the spec/install manual for the unit. Does your high voltage wire correspond to 40 or 30A?
  13. Don2222

    Don2222 Minister of Fire

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    Hi woodgeek

    Many thanks for those numbers. I agree that 30 Amps is probably what was in the manual years ago and that is why a 30amp breaker was installed into the main panel for this unit. Not sure about the gauge of the wiring but if I get another peek I will check. The outside disconnect for easy servicing is a 60 amp breaker which of course never trips.
  14. basod

    basod Minister of Fire

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    The outside disconnect is not a "breaker" it is a disconnect that is capabale of interupting the current rating if manually thrown.
  15. Don2222

    Don2222 Minister of Fire

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    Understood, but in this case to accomplish the disconnect, it looks like they used a 60 amp breaker.

    See pic
    Click to enlarge.
    Says 60 on the bar that joins the 2 breakers

    Attached Files:

  16. heat seeker

    heat seeker Minister of Fire

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    Around here, that's not done - putting a breaker outside, even in a watertight box. They use a simple disconnect where you pull a piece out that breaks the circuit. It's just for the serviceman's safety.
  17. seige101

    seige101 Minister of Fire

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    The better question is why there is a 240 volt outlet off the side of the disconnect, especially without a weather proof cover on it.
  18. heat seeker

    heat seeker Minister of Fire

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    Good point! This electrical work is beginning to look suspect.
  19. woodgeek

    woodgeek Minister of Fire

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    My codes require a 120V 'convenience' outlet be installed near the condenser. Is it really a 240V outlet, or a 120 wired to a separate circuit?
  20. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    It appears the hand is holding open the outlet cover.
  21. Don2222

    Don2222 Minister of Fire

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    Correct Smokey it is a weather proof cover I am holding up. How ever the outlet is 240v on the same circuit! I tested it with my DVM!
  22. SmokeyTheBear

    SmokeyTheBear Minister of Fire

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    Don,

    Have you tried redoing all of the wire connections removing any oxidation and providing a bit of protective conductive coating?

    What is the HP of the compressor and does it and the fan motors start at the same time?
  23. ROVERT

    ROVERT Member

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    I strongly suspect that someone (probably a homeowner) wired that receptacle on there to be used as the feed off of a back up generator. Probably not how I would do it, but I don't see why it wouldn't work. I've seen a number of disconnects with breakers for condensing units. Pull-out disconnects are definitely more widely used. I'm not sure why that one has a 60A breaker. Someone probably just had it lying around and decided to put it to use. It doesn't really matter as long as the breaker in the main panel is a 30 A and the wire is 10 ga or larger.

    As to the air conditioner, you can try throwing a hard start capacitor at it, but I suspect the compressor is in the throes of death.

    You should not put a 40 A breaker in the main panel unless that is what is listed on the unit. If the unit does allow for a 40 A breaker you need to make sure that the wiring is adequate. I really don't think this is the problem though. Except for a bad connection somewhere, I think you're looking at a compressor problem. The unit obviously ran for a number of years on a 30A breaker, there is no reason to think that upping the breaker size now is a way to fix it.
    blujacket likes this.
  24. Don2222

    Don2222 Minister of Fire

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    Hi Smokey

    It was working fine for about a week, now the compressor is making some nasty noises.
    Does anyone know if the compressor can be fixed for a low price?

    All the Central AC techs in this area do not want to mess with an older R22 system. They all want from 3 - 5k to replace the compressor and evaporator and use the newer freon!
  25. velvetfoot

    velvetfoot Minister of Fire

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    Can you buy a replacement heat pump that's good in cold weather?
    It could at least take care of the shoulder seasons, maybe cheaper than pellets.
    How about something like this?:
    http://www.carriergreenspeed.com/

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