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sunrisetosunset's avatar
sunrisetosunset
Explorer
Jun 22, 2014

air conditioner has quit working

our common (now about 12 years old with us being the original owners) roof mount air conditioner has quit working. for some time now (about a year or so with us using the camper sparingly over that time) when put in cool mode at the wall mount thermostat it would come on fine but began to act up a little as follows: when not actually running i would hear a humming sound coming from the roof area (air conditioner location ofc) but when temp required it to come on or i slid the control down i would get 'normal' operation of the ac. however since i didn't feel the humming when not being ON was a good thing i would turn the ac breaker in the camper to off until i needed it again. this went on like this until about a month or two ago when i noticed the campers ac breaker was tripping, but if i slid it down and back up again everything would go back to what i just described; hum when not actually running but run fine in cool required mode. this past week it pretty much quit entirely when my wife turned it on as i told her to (slide the break down then back up and slide the temp control to what we needed) which she did and apparantly it worked as before but then when i went in the camper about a half hour after she had done it i noticed there was nothing from the ac. no cool no hum. so i tripped the breaker back down and back up and got nothing. went outside to check power cord and my own personal pedestal power panel and breaker there was not tripped and all other electrical things SEEMED to be working (not that i actually checked anything but i DID notice that the 'house' fan was running normal (not the ac fan but a fan fan on the ceiling).
so i went and tripped the camper breaker once more and back up and heard the hum so slid the control to cool and nothing......tripped the breaker back down and back up and nothing not even the hum.....any help in troubleshooting is greatly appreciated....i'm not THE best mechanic in the world but i do farm for a living and have to do a LOT of things around here and wear a lot of hats so i might be able tofigure it out with some guidance on what to check and where ....thanks in advance gary
  • nomad297's avatar
    nomad297
    Explorer
    Jun 22, 2014
    Ouch......I tried reading your post, but my eyes and brain could only make it to the third or fourth line before they broke down.

    Bruce
  • Ranger_Smith's avatar
    Ranger_Smith
    Explorer
    Jun 22, 2014
    The humming was the compressor running constantly due to a bad control board. Had same problem with one of mine. The compressor is probably locked up and that is why breaker is tripping. Could also be a bad start capacitor
  • tandkj's avatar
    tandkj
    Explorer
    Jun 22, 2014
    Just fixed mine, new start capacitor and new motor. Cost around $400. New a/c $1400. Went out and spend the $1000 difference on booze and a woman. Now having to pay $10,000 for a divorce.
  • Bob_Landry's avatar
    Bob_Landry
    Explorer
    Jun 22, 2014
    nomad297 wrote:
    Ouch......I tried reading your post, but my eyes and brain could only make it to the third or fourth line before they broke down.

    Bruce


    You made further than I did.
  • ksg5000's avatar
    ksg5000
    Explorer
    Jun 22, 2014
    Seem to recall early posts from you where your AC would hum when it wasn't "on" - think you were advised to buy new thermostat and control board ... did that ever happen?
  • wwest's avatar
    wwest
    Explorer
    Jun 22, 2014
    " Our common....roof mount air conditioner.."

    Is NOT so common! Having a wall thermostat to control an RV A/C is not "common" by any means.

    10 years...time to clean both the condenser, evaporator, and BOTH fans.

    It sounds as if any time the CB is on the A/C fan is running (humming). Very likely the thermostat operates a relay in the A/C that interrupts the A/C compressor circuit when the thermostat setting is satisfied.

    Also possible that the "humming" doesn't cease but is "overshadowed" by the compressor noise?
  • wwest's avatar
    wwest
    Explorer
    Jun 22, 2014
    sunrisetosunset wrote:
    our common (now about 12 years old with us being the original owners) roof mount air conditioner has quit working.

    for some time now (about a year or so with us using the camper sparingly over that time) when put in cool mode at the wall mount thermostat it would come on fine but began to act up a little as follows:

    when not actually running i would hear a humming sound coming from the roof area (air conditioner location ofc) but when temp required it to come on or i slid the control down i would get 'normal' operation of the ac.

    however since i didn't feel the humming when not being ON was a good thing i would turn the ac breaker in the camper to off until i needed it again.

    this went on like this until about a month or two ago when i noticed the campers ac breaker was tripping, but if i slid it down and back up again everything would go back to what i just described; hum when not actually running but run fine in cool required mode.

    this past week it pretty much quit entirely when my wife turned it on as i told her to (slide the break down then back up and slide the temp control to what we needed) which she did and apparantly it worked as before but then when i went in the camper about a half hour after she had done it i noticed there was nothing from the ac.

    no cool no hum. so i tripped the breaker back down and back up and got nothing. went outside to check power cord and my own personal pedestal power panel and breaker there was not tripped and all other electrical things SEEMED to be working (not that i actually checked anything but i DID notice that the 'house' fan was running normal (not the ac fan but a fan fan on the ceiling).

    so i went and tripped the camper breaker once more and back up and heard the hum so slid the control to cool and nothing......tripped the breaker back down and back up and nothing not even the hum.....

    any help in troubleshooting is greatly appreciated....i'm not THE best mechanic in the world but i do farm for a living and have to do a LOT of things around here and wear a lot of hats so i might be able tofigure it out with some guidance on what to check and where ....thanks in advance gary


    Does the humming sound co-inside with A/C outlet airflow?

    Sounds as if your wall mounted thermostat has a cool/off/(heat?) control switch along with an actual thermostatic temperature sensing (mercury?) switch.

    Common arrangement is the switch in "cool" position directly controls the fan motor which is likely the humming sound you hear, and also "enables" the operation of the A/C compressor thermostat control relay.

    Turning the thermostat switch from "cool" to off, or opening the CB, will stop the A/C "humming" fan motor.

    Although it seems highly improbable it appears that some idiot has wired only one "phase" of the compressor motor power through the thermostat control relay. Most RV A/C systems use a capacitor start winding that is only engaged to provide an induction motor startup period.

    With the CB and "cool" switch "on" and energizing only the start winding would be most certainly result in an audiable "humming" sound/noise that would disappear once the compressor motor actually starts running.

    Or...Starting relay stuck closed?
  • sunrisetosunset's avatar
    sunrisetosunset
    Explorer
    Jun 22, 2014
    thanks for all the input y'all...i am a cut flower farmer AND a basket maker and we are having to down size and sell our farm thanks to the soft economy so i won't be able to get back to this immediately (and yes that likely was my earlier post..things don't happen quickly here when you have so many irons in the fire) but i willprint out the USEFUL answers and to those who took the time to ALMOST read my post may i say my apologies for my trying to input as much info as possible......i know how hard it is to help someone trouble shoot something that isn't there with you..it's SO nice to have JUST as MUCH info as possible....and yes my writing style is a bit scattered.....i get it....sooooo....in the interest of being MOST helpful to you ..let me say this....putting on-off switch into on position doesn't make machine work. please help kind sirs. :)
    as soon as i have the time to try some of this and eliminate things i will report back but it won't be today
    oh and sorry for my snippiness just now but i'm a bit overwhelmed atm. ik sux to be me np i can do this
    thanks again to ALL i find this forum to be invaluable asset and pass along the good will and intent as often as i am able.

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