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    Denali's Avatar
    Denali Posts: 7, Reputation: 1
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    #1

    Jun 9, 2007, 05:42 AM
    Central Air Conditioner Unit does not work
    Quote Originally Posted by mississippidavid
    my central air conditioner unit ( outside) does not work.. .. When i apply power to the unit the fan does not turn on but the unit makes a buzzing sound every 15 seconds or so .. it sounds like it wants to start but cannot .. if i stand beside the unit, the fan does not turn but every 10-20 seconds i here a buzzing sound and then it quits

    -- can you tell me what could be wrong with the unit and identify what part(s) will need to be replaced

    or can you tell me what trouble shooting tips you can give to identify what part is needed

    thanks
    I'll try to keep this as short as possible but I've been fighting the problem for over a month now and it's getting a tad warm here in Las Vegas. My problem is very similar to MSdavid's.

    I had a similar problem last July and the A/C repair guy replaced the run capacitor which resolved the problem until last month. The biggest difference is that presently (and last year) the fan won't start up and run. The biggest difference between my problem and MSdavid's is that I can give the fan a manual "flip" and then the fan will get up to speed and run -- for a while. Last year the flip would get things going until the thermostat was satisfied. Now, the unit runs for just a few minutes and then shuts down.

    I had the repairman check it last month and he quoted $500 to replace the fan motor. He installed a different run capacitor and that didn't help. Being retired and on limited income, I couldn't afford that so I purchased a new motor and intalled it myself. The problem persists.

    So, my question is, what should I suspect now? With both a new capacitor and new motor I'm stymied.
    Thanks
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
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    #2

    Jun 9, 2007, 09:32 AM
    The main question is did you wire the new motor correctly? When the motor shuts off is the motor hot to the touch?
    Denali's Avatar
    Denali Posts: 7, Reputation: 1
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    #3

    Jun 9, 2007, 05:05 PM
    Thanks for your response.

    The A/C tech did change the run capacitor from a three connector type to a two connector while attempting to convince me that the motor was bad.

    He was out here a week or so before and said the motor was bad and, as I said, wanted $500 to replace it.

    I knew I could change it for far less so I took the old motor out and took it to a motor service center. The service center said they wanted to test the old motor before selling a new one to me. After testing I was told there was nothing wrong with the motor and that they didn't want to sell me a new one. I figured that if they were honest enough to not sell me a new one, the old one must truly be okay. So I put it back in the unit and called the tech. It was during this visit that he changed the run capacitor and rather vehemently insisted that the motor was bad.

    The shop that had tested the motor was closed by the time the tech left so I went to a different one to buy a new motor and, hopefully, get some relief from the Las Vegas heat.

    The shop where I bought the new motor transferred the blade from old to new. They also cut the wiring harness with the cabinet plug off the old motor and put it on the new one. So, it was pretty much a turnkey operation. They also matched the specs for the run capacitor to be sure it was the right one. The only caution they gave me was to point out a connector they had installed so that, if the fan rotation was wrong, I could simply rotate the connector and change the rotation. (see below)

    Is the motor hot when it shuts down? I don't mean to be a smart but, yes, I wouldn't expect it to be otherwise. Just sitting in the Las Vegas sun keeps it hot enough to fry and egg on it.

    Before you ask, the fan is properly installed on the motor. It is blowing air out of the compressor housing. As I mentioned before, I can give the fan blade a little flip and the motor will come up to speed for around 25 minutes. Then the fan shuts down and the compressor goes into high pressure bypass. I use a painters stirring paddle to flip the blade. When the fan is running there is a strong movement of air and if I try to set the stir stick on the fan grille it gets blown off immediately.

    As I said, thanks for your reply. If there's anything else you need to know to help me resolve this problem, let me know.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
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    #4

    Jun 9, 2007, 06:24 PM
    The fan should not be shutting down. The motor is going out on internal overload. The motor might need to be a larger horse power. Many times the factory motor is specific to a unit and is designed for that unit. Unless you got the motor from a company that sells your brand of unit it could be a problem. What is the name and model number of your unit? I will try to look up to see what the exact specifications are.
    NorthernHeat's Avatar
    NorthernHeat Posts: 1,455, Reputation: 132
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    #5

    Jun 10, 2007, 08:59 AM
    Need to take a amp check on the motor while in operation inside the unit. If the contacts on the fan relay are bad, motor can start but the voltage drop across contacts to the motor will cause the motor to pull high amps, (see rating plate on equipment) causing the motor to overheat and shut down on thermal overload. Yes, motors get hot to the touch but you should be able to hold your hand on it for quite a long time before it is painfully hot.
    Denali's Avatar
    Denali Posts: 7, Reputation: 1
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    #6

    Jun 11, 2007, 10:44 PM
    Quote Originally Posted by hvac1000
    The fan should not be shutting down. The motor is going out on internal overload. The motor might need to be a larger horse power. Many times the factory motor is specific to a unit and is designed for that unit. Unless you got the motor from a company that sells your brand of unit it could be a problem. What is the name and model number of your unit? I will try to look up to see what the exact specifications are.
    Sorry it's taken me so long to get back to you. Here's all the info I can find;
    Evcon Industries
    Model: BRCS0601BB
    Ser.:950509114
    BTU: 60K
    Compressor:230V RLA 24.4
    Fan Motor: 230V 1/3HP

    Again, what's happening is that when the termostat calls for cooling, the compressor comes on but the fan doesn't. If I give the fan a "flip" it starts and expels LOTS of hot air - for as long as it runs. It seems to run, most of the time, for about 20 minutes and then the fan shuts down (and the motor is extremely hot to the touch) and the compressor continues in high pressure bypass.

    Any help would be most appreciated.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
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    #7

    Jun 11, 2007, 11:50 PM
    Here is the factory info for your outside condenser fan motor.

    Old number for motor is (1468-414P)

    New number is 024-27596-700 Condenser Fan Motor (( VENDOR A.O. Smith ))

    1/4 hp single speed 208-230V fan motor for condensers. 850 RPMs, 1.5 amps. Requires a run capacitor ((5 MFD/370V CAPACITOR )). Replaces 024-27596-000, 024-26022-000, 024-14806-000, 1468-413P, 1468-414P, 024-26021-000, 024-27585-000 & 024-26068-000.

    Blade is a 22 inch three blade, one half inch motor bore, 34 degree pitch CW facing air discharge. Aluminum construction.

    This info is from the Coleman/Evcon dealer network site.

    I am bringing this to your attention because if the specs on the motor you have is different from above that can be your problem. Usually the wrong motor speed causes the problem with motor overload conditions such as whet you have described. You might have been given a 1075/1100 RMP motor. If that is the case it will be overloaded. You to check to be sure you have a 825 RPM motor. Faster is not always better. Always remember to use the correct capacitor and change it whenever you change the motor.

    There is no reason to have to manually flip the blade to get it going unless the motor has a flat spot or the capacitor is defective. NOTE: sometimes new capacitors are bad when brand new.
    Denali's Avatar
    Denali Posts: 7, Reputation: 1
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    #8

    Jun 13, 2007, 10:59 AM
    Hey All,
    Thanks for the helpful suggestions.

    I pulled the motor yesterday and took it back to the shop where I bought it. Sure enough, they had two of the wires switched. I brought it home, reinstalled it and the A/C has been keeping us cool and comfortable for 24 hours now.
    cotton06's Avatar
    cotton06 Posts: 1, Reputation: 1
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    #9

    May 12, 2011, 08:14 AM
    I have an outside a/c that doesn't have a model number tag or name, how do I find it?
    roadbuilder's Avatar
    roadbuilder Posts: 1, Reputation: 1
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    #10

    Aug 7, 2011, 07:57 AM
    I started having problems with my ac so I changed the thermostat,the relay,and the capacitor.that was yestarday the compressor worked fine but the airhandler would shut down when the compressor kicked in, now today the airhandler will run but the compressor won't start up. The model# is PF1MNB030, the product# PF1MNB030000AAAA,serial# 1004A80638,motor hp 1/4-1.5 volts 208/230 phase 1/60
    VoiceofReasonNK's Avatar
    VoiceofReasonNK Posts: 5, Reputation: 1
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    #11

    Aug 1, 2012, 06:12 AM
    I just had the same problem. I replaced the motor with no luck. It turned out to be a bad capacitor. If it is a dual capacitor, three prongs on top, it also starts the compressor. It is recommended to replace the capacitor anytime you replace a motor. I would try replacing the capacitor first. It is a lot cheaper that a new motor. If that does not fix the problem then you can get a motor. No harm, no foul. The slow start of the motor is a common symptom of a bad capacitor. The motor is not getting enough voltage. The capacitor increases the voltage like a transformer. It will boost it to almost 400 volts, depending on your unit.

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