Air conditioner comes on for 10 seconds or so and kicks back off again, any ideas?

Discussion in 'Misc DIY' started by Mike, Aug 30, 2007.

  1. Mike

    Mike Guest

    Hi everyone.

    I have a central air conditioning unit in my ranch-style home (full
    basement also). Yesterday the AC just kicked off randomly. I checked
    the thermostat and it seemed to be functioning ok (it's digital). I
    went downstairs to the power switch dedicated to the central air unit
    and turned it off, then back on again. The AC kicked back on, stayed
    on and started blowing cool air, then kicked back off again 2 minutes
    later.

    I suspected there was an airflow problem of some type (filter, etc)
    but that doesn't appear to be case, at least not as far as I can
    tell.

    Are there any other common causes for this type of behavior?

    Thank you for any responses,
    Mike
    Mike, Aug 30, 2007
    #1
  2. Mike

    Eric Guest

    Check the outside unit. Is the fan turning at normal speed? Anything blocking the airflow?

    If the outside unit wasn't getting enough airflow, the high-pressure switch could cause it to cut out.

    Also could be a problem with the compressor motor, start circuit, or capacitor, causing the thermal overload to trip.

    Eric Law

    "Mike" <> wrote in message news:...
    > Hi everyone.
    >
    > I have a central air conditioning unit in my ranch-style home (full
    > basement also). Yesterday the AC just kicked off randomly. I checked
    > the thermostat and it seemed to be functioning ok (it's digital). I
    > went downstairs to the power switch dedicated to the central air unit
    > and turned it off, then back on again. The AC kicked back on, stayed
    > on and started blowing cool air, then kicked back off again 2 minutes
    > later.
    >
    > I suspected there was an airflow problem of some type (filter, etc)
    > but that doesn't appear to be case, at least not as far as I can
    > tell.
    >
    > Are there any other common causes for this type of behavior?
    >
    > Thank you for any responses,
    > Mike
    >
    Eric, Aug 30, 2007
    #2
  3. Mike

    Mike Guest

    On Aug 30, 3:40 pm, wrote:
    > On Thu, 30 Aug 2007 19:22:10 -0000, Mike <>
    > wrote:
    >
    >
    >
    > >Hi everyone.

    >
    > >I have a central air conditioning unit in my ranch-style home (full
    > >basement also). Yesterday the AC just kicked off randomly. I checked
    > >the thermostat and it seemed to be functioning ok (it's digital). I
    > >went downstairs to the power switch dedicated to the central air unit
    > >and turned it off, then back on again. The AC kicked back on, stayed
    > >on and started blowing cool air, then kicked back off again 2 minutes
    > >later.

    >
    > >I suspected there was an airflow problem of some type (filter, etc)
    > >but that doesn't appear to be case, at least not as far as I can
    > >tell.

    >
    > >Are there any other common causes for this type of behavior?

    >
    > >Thank you for any responses,
    > >Mike

    >
    > The compressor may be drawing to much current and a bi-metallic
    > safety switch is shutting it down or the cooling fan for the coil is
    > not functioning and causing a over temp fault.


    I'm not really an AC expert, so the items I see to check:
    1) Fan on the compressor unit outside the house
    2) Ensure nothing is blocking airflow in or around the outside unit
    3) Compressor drawing too much current (any way to check this, I do
    have a multimeter)
    Mike, Aug 30, 2007
    #3
  4. Mike

    Joe Guest

    On Aug 30, 4:49 pm, Mike <> wrote:

    >snip<


    > 3) Compressor drawing too much current (any way to check this, I do
    > have a multimeter)


    You need an AC ammeter or the right adapter to handle 50 A more or
    less on your multimeter. HTH

    Joe
    Joe, Aug 30, 2007
    #4
  5. Mike

    dpb Guest

    Re: Air conditioner comes on for 10 seconds or so and kicks backoff again, any ideas?

    Joe wrote:
    > On Aug 30, 4:49 pm, Mike <> wrote:
    >
    >> snip<

    >
    >> 3) Compressor drawing too much current (any way to check this, I do
    >> have a multimeter)

    >
    > You need an AC ammeter or the right adapter to handle 50 A more or
    > less on your multimeter. HTH


    Quite an adapter to put inline w/ a conventional multimeter... :)

    In a practical sense, unless you have a clampon meter, no, there isn't
    an easy way for large currents...typical VOM's are able to handle only a
    few 10's of mA.

    --
    dpb, Aug 30, 2007
    #5
  6. Mike

    Jon Danniken Guest

    "dpb" wrote:
    > Joe wrote:
    >> On Aug 30, 4:49 pm, Mike <> wrote:
    >>
    >>> snip<

    >>
    >>> 3) Compressor drawing too much current (any way to check this, I do
    >>> have a multimeter)

    >>
    >> You need an AC ammeter or the right adapter to handle 50 A more or
    >> less on your multimeter. HTH

    >
    > Quite an adapter to put inline w/ a conventional multimeter... :)


    All you need is a length of wire (or a resistor) to use as a shunt, inserted
    in parallel with the load.

    > In a practical sense, unless you have a clampon meter, no, there isn't an
    > easy way for large currents...typical VOM's are able to handle only a few
    > 10's of mA.


    My cheapy Harbor Freight DMM measures up to 20A AC current, but most common
    meters usually only measure a few hundred mA of DC current.

    Jon
    Jon Danniken, Aug 31, 2007
    #6
  7. Mike

    dpb Guest

    Re: Air conditioner comes on for 10 seconds or so and kicks backoff again, any ideas?

    Jon Danniken wrote:
    > "dpb" wrote:
    >> Joe wrote:
    >>> On Aug 30, 4:49 pm, Mike <> wrote:
    >>>
    >>>> snip<
    >>>> 3) Compressor drawing too much current (any way to check this, I do
    >>>> have a multimeter)
    >>> You need an AC ammeter or the right adapter to handle 50 A more or
    >>> less on your multimeter. HTH

    >> Quite an adapter to put inline w/ a conventional multimeter... :)

    >
    > All you need is a length of wire (or a resistor) to use as a shunt, inserted
    > in parallel with the load.


    Yeah, but...if needed to ask, that's not just a "just" w/ 50A...

    --
    dpb, Aug 31, 2007
    #7
  8. Mike

    Moe Jones Guest

    Mike wrote:
    > Hi everyone.
    >
    > I have a central air conditioning unit in my ranch-style home (full
    > basement also). Yesterday the AC just kicked off randomly. I checked
    > the thermostat and it seemed to be functioning ok (it's digital). I
    > went downstairs to the power switch dedicated to the central air unit
    > and turned it off, then back on again. The AC kicked back on, stayed
    > on and started blowing cool air, then kicked back off again 2 minutes
    > later.
    >
    > I suspected there was an airflow problem of some type (filter, etc)
    > but that doesn't appear to be case, at least not as far as I can
    > tell.
    >
    > Are there any other common causes for this type of behavior?
    >
    > Thank you for any responses,
    > Mike


    When you say that you turned off the power switch, are you talking about the
    120-volt toggle switch?

    If that is all you did, you had to have reset something and it could be a
    number of things. Your thermostat, safety control or control board. Your
    best bet is call out your HVAC company to have them check pout your system.

    --
    Moe Jones
    HVAC Service Technician
    Energy Equalizers Inc.
    Houston, Texas
    www.EnergyEqualizers.com
    Moe Jones, Aug 31, 2007
    #8
  9. Mike

    Red Guest

    On Aug 30, 2:22 pm, Mike <> wrote:
    > Hi everyone.
    >
    > I have a central air conditioning unit in my ranch-style home (full
    > basement also). Yesterday the AC just kicked off randomly. I checked
    > the thermostat and it seemed to be functioning ok (it's digital). I
    > went downstairs to the power switch dedicated to the central air unit
    > and turned it off, then back on again. The AC kicked back on, stayed
    > on and started blowing cool air, then kicked back off again 2 minutes
    > later.
    >
    > I suspected there was an airflow problem of some type (filter, etc)
    > but that doesn't appear to be case, at least not as far as I can
    > tell.
    >
    > Are there any other common causes for this type of behavior?
    >
    > Thank you for any responses,
    > Mike


    Define "kicked off/kicked on". Do you mean the inside unit, the
    outside unit, or both. IIRC, all the talk about the compressor
    "kicking off" would be related to the outside unit only. If the inside
    blower was "kicking off", that would be a whole different problem than
    the compressor. At least that's how my residential unit works.
    Red, Aug 31, 2007
    #9
  10. Re: Air conditioner comes on for 10 seconds or so and kicks backoff again, any ideas?

    Mike wrote:
    > Hi everyone.
    >
    > I have a central air conditioning unit in my ranch-style home (full
    > basement also). Yesterday the AC just kicked off randomly. I checked
    > the thermostat and it seemed to be functioning ok (it's digital). I
    > went downstairs to the power switch dedicated to the central air unit
    > and turned it off, then back on again. The AC kicked back on, stayed
    > on and started blowing cool air, then kicked back off again 2 minutes
    > later.
    >
    > I suspected there was an airflow problem of some type (filter, etc)
    > but that doesn't appear to be case, at least not as far as I can
    > tell.
    >
    > Are there any other common causes for this type of behavior?
    >
    > Thank you for any responses,
    > Mike
    >


    If your AC condensing unit is equipped with a low
    pressure cut off switch, it can make the unit cut
    on and off due to a low freon charge. Unless you
    know your way around HVAC systems and have the
    proper tools and equipment, you should call someone
    who does.

    [8~{} Uncle Monster
    Uncle Monster, Aug 31, 2007
    #10
  11. Re: Air conditioner comes on for 10 seconds or so and kicks backoff again, any ideas?

    Telstra wrote:
    > "Mike" <> wrote in message
    > news:...
    >> Hi everyone.
    >>
    >> I have a central air conditioning unit in my ranch-style home (full
    >> basement also). Yesterday the AC just kicked off randomly. I checked
    >> the thermostat and it seemed to be functioning ok (it's digital). I
    >> went downstairs to the power switch dedicated to the central air unit
    >> and turned it off, then back on again. The AC kicked back on, stayed
    >> on and started blowing cool air, then kicked back off again 2 minutes
    >> later.
    >>
    >> I suspected there was an airflow problem of some type (filter, etc)
    >> but that doesn't appear to be case, at least not as far as I can
    >> tell.
    >>
    >> Are there any other common causes for this type of behavior?
    >>
    >> Thank you for any responses,
    >> Mike
    >>

    >
    > There are a number of controls in series with the cooling
    > relay. Anti recycle timer, HP/LP control and compressor
    > thermal and current Overload.. However the HP control is
    > normally a manual reset and the LP auto reset so the Unit
    > as Uncle monster said is probably cycling on the LP control
    > which indicates a loss of refrigerant charge


    It's not unusual for me and my guys to add those
    controls to a contractor grade condensing unit.
    I also add a head pressure control to those AC
    systems installed in restaurants since the units
    are run year round. If there is no electronic
    thermostat with a built in anti-short cycle timer,
    an inexpensive timer module installed in the
    condensing unit can save an expensive compressor
    from those people who like to play with thermostats.
    It's often very difficult to convince some folks
    to spend money on preventive maintenance.

    [8~{} Uncle Monster
    Uncle Monster, Aug 31, 2007
    #11
  12. Mike

    David Combs Guest

    In article <>,
    Mark Lloyd <10.invalid> wrote:
    >On Thu, 30 Aug 2007 17:34:36 -0500, dpb <> wrote:
    >
    >>Joe wrote:
    >>> On Aug 30, 4:49 pm, Mike <> wrote:
    >>>
    >>>> snip<
    >>>
    >>>> 3) Compressor drawing too much current (any way to check this, I do
    >>>> have a multimeter)
    >>>
    >>> You need an AC ammeter or the right adapter to handle 50 A more or
    >>> less on your multimeter. HTH

    >>
    >>Quite an adapter to put inline w/ a conventional multimeter... :)
    >>
    >>In a practical sense, unless you have a clampon meter, no, there isn't
    >>an easy way for large currents...typical VOM's are able to handle only a
    >>few 10's of mA.

    >
    >Some do have a 10A range (with a separate jack). I used to use that
    >frequently to measure the current use by 120V appliances.
    >--
    >Mark Lloyd
    >http://notstupid.laughingsquid.com
    >
    >"God was invented by man for a reason, that
    >reason is no longer applicable."



    Question: are the clamp-ons at all accurate, or are they
    (sometimes) GROSSLY wrong?

    EG I got a radio shack 2part vom that had a plug-in clamp-on
    coming with it. (maybe $30 when I got it 3 or so yrs ago)

    David
    David Combs, Sep 22, 2007
    #12
  13. Mike

    Guest

    On Aug 31, 3:50 am, Uncle Monster <> wrote:
    > Telstra wrote:
    > > "Mike" <> wrote in message
    > >news:...
    > >> Hi everyone.

    >
    > >> I have a central air conditioning unit in my ranch-style home (full
    > >> basement also). Yesterday the AC just kicked off randomly. I checked
    > >> the thermostat and it seemed to be functioning ok (it's digital). I
    > >> went downstairs to the power switch dedicated to the central air unit
    > >> and turned it off, then back on again. The AC kicked back on, stayed
    > >> on and started blowing cool air, then kicked back off again 2 minutes
    > >> later.

    >
    > >> I suspected there was an airflow problem of some type (filter, etc)
    > >> but that doesn't appear to be case, at least not as far as I can
    > >> tell.

    >
    > >> Are there any other common causes for this type of behavior?

    >
    > >> Thank you for any responses,
    > >> Mike

    >
    > > There are a number of controls in series with the cooling
    > > relay. Anti recycle timer, HP/LP control and compressor
    > > thermal and current Overload.. However the HP control is
    > > normally a manual reset and the LP auto reset so the Unit
    > > as Uncle monster said is probably cycling on the LP control
    > > which indicates a loss of refrigerant charge

    >
    > It's not unusual for me and my guys to add those
    > controls to a contractor grade condensing unit.
    > I also add a head pressure control to those AC
    > systems installed in restaurants since the units
    > are run year round. If there is no electronic
    > thermostat with a built in anti-short cycle timer,
    > an inexpensive timer module installed in the
    > condensing unit can save an expensive compressor
    > from those people who like to play with thermostats.
    > It's often very difficult to convince some folks
    > to spend money on preventive maintenance.
    >
    > [8~{} Uncle Monster- Hide quoted text -
    >
    > - Show quoted text -


    If it was low on charge, why would it kick back on and blow cold air?
    If you want to be sure that it's not a control problem, remove the
    face of the thermostst and install a jumper between the R,G, and Y
    terminals. If the A.C. runs continually and cools effectively, replace
    the t-stat.

    PS: Don't worry, it's only 24volts. Be careful if there is a "C or B"
    terminal that you don't touch them with the jumper as you could blow a
    transformer fuse.
    , Sep 22, 2007
    #13
  14. Mike

    CJT Guest

    Re: Air conditioner comes on for 10 seconds or so and kicks backoff again, any ideas?

    David Combs wrote:

    > In article <>,
    > Mark Lloyd <10.invalid> wrote:
    >
    >>On Thu, 30 Aug 2007 17:34:36 -0500, dpb <> wrote:
    >>
    >>
    >>>Joe wrote:
    >>>
    >>>>On Aug 30, 4:49 pm, Mike <> wrote:
    >>>>
    >>>>
    >>>>>snip<
    >>>>
    >>>>>3) Compressor drawing too much current (any way to check this, I do
    >>>>>have a multimeter)
    >>>>
    >>>>You need an AC ammeter or the right adapter to handle 50 A more or
    >>>>less on your multimeter. HTH
    >>>
    >>>Quite an adapter to put inline w/ a conventional multimeter... :)
    >>>
    >>>In a practical sense, unless you have a clampon meter, no, there isn't
    >>>an easy way for large currents...typical VOM's are able to handle only a
    >>>few 10's of mA.

    >>
    >>Some do have a 10A range (with a separate jack). I used to use that
    >>frequently to measure the current use by 120V appliances.
    >>--
    >>Mark Lloyd
    >>http://notstupid.laughingsquid.com
    >>
    >>"God was invented by man for a reason, that
    >>reason is no longer applicable."

    >
    >
    >
    > Question: are the clamp-ons at all accurate, or are they
    > (sometimes) GROSSLY wrong?
    >


    Even the $12 ones at Harbor Freight seem to do a pretty good job.

    > EG I got a radio shack 2part vom that had a plug-in clamp-on
    > coming with it. (maybe $30 when I got it 3 or so yrs ago)
    >
    > David
    >
    >



    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form .
    CJT, Sep 22, 2007
    #14
  15. Mike

    Mike S. Guest

    A quality clamp on meter is VERY accurate, and they are used all the time by
    professionals to measure current. That's how large currents are measured.
    Here are some examples
    http://us.fluke.com/usen/products/category.htm?category=CLMP(FlukeProducts)

    A $30 Radio Shack meter could be good or could be bad, but I wouldn't trust
    it personally.

    --

    Mike S.

    "David Combs" <> wrote in message
    news:fd3qoh$qbl$...
    >
    > Question: are the clamp-ons at all accurate, or are they
    > (sometimes) GROSSLY wrong?
    >
    > EG I got a radio shack 2part vom that had a plug-in clamp-on
    > coming with it. (maybe $30 when I got it 3 or so yrs ago)
    >
    > David
    >
    >
    Mike S., Sep 22, 2007
    #15
  16. Mike

    CJT Guest

    Re: Air conditioner comes on for 10 seconds or so and kicks backoff again, any ideas?

    Mike S. wrote:

    > A quality clamp on meter is VERY accurate, and they are used all the time by
    > professionals to measure current. That's how large currents are measured.
    > Here are some examples
    > http://us.fluke.com/usen/products/category.htm?category=CLMP(FlukeProducts)
    >
    > A $30 Radio Shack meter could be good or could be bad, but I wouldn't trust
    > it personally.
    >


    It's easy enough to check one out with a known current or by comparison
    with an inline meter with a known-good calibration.

    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form .
    CJT, Sep 22, 2007
    #16

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