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Alfred622's avatar
Alfred622
Explorer
Jun 26, 2014

A/C Stall when first starting - what could be wrong?

I'd be looking for any tips if anyone has seen this problem before.

2005 Winnebago, single roof airconditioner. After not being used for months, I will get a non-start the first time. After that, it seems to cycle fine.

By Non start, I mean: I set the Thermostat to Cool, Fan to Auto, and start. I hear the thermostat relay clicks then the fan in the A/C unit starts to run. I hear a groan from the roof A/C like the compressor is starting, but it shuts down within 1 second. Now Roof air stops too and all is very quiet. If I wait 20 or 3O minutes, and try turning the thermostat to cool, this time the A/C might kick in and be just fine.

Any suggestions as to where the problem could be? I k now my voltage has always been over 110v.

Does this sound like a starting capacitor... or something else?
Class A
  • Golden_HVAC's avatar
    Golden_HVAC
    Explorer
    Jun 26, 2014
    Hi,

    This picture was posted a few days ago. It shows the start capacitors for both the fan with brown wires and compressor with red and yellow wires. This post was about how to install a additional start capacitor, such as the SPP4E rated at 90 to 130 volts. This provides a extra "Kick" to get the compressor started.

    You might have a bad run capacitor (the one with Herm and common or in this picture they are separate, and has the red and yellow wires.) or one that is to weak. I have tested some capacitors and find that some will read 30 MFD while the rating is 35 MFD +/- 10% (or 3.5 MFD), so I replaced the capacitor, and all worked well again, the amperage has gone back to normal.

    Make sure that you do not buy the SPP6E rated at 190 to 280 volts.

    Golden_HVAC wrote:
    Beyer wrote:
    I have a 1996 camper with a Coleman A/C. I bought the Supco SPP6E. My A/C has 2 round capacitors, one small and one large. The small one has 2 wires and the large has 3 wires. Which one do I replace? Both?
    Pics:

    http://i1372.photobucket.com/albums/ag321/beyer25/Mobile%20Uploads/image_zpsf3f66b5c.jpg






    The small capacitor with wires going to the outside fan is the wrong capacitor. THe one with wires going to the compressor is the correct one. Typically the red and another color wire go to the compressor along with a black one. Don't connect to the black one. Use the red wire and yellow wires. You want those two connections.

    You do NOT take out the factory capacitor, just add the second one to the compressor circuit to help shorten the time it spends in "Locked rotor" amperage, and shorten the time it takes to get up to full speed.

    Make SURE that you put a screw into the existing capacitors tie down strap, or it can short to ground if the metal from the wires shorts our to the metal of the clamp.

    If your compressor is not working right, then replace the small round capacitor with the red and yellow wires on it. It might be 25 MFD or 35 MFD, replace with the same size. Shape is less important, you probably can find one for about $10 that is oval, or round one for a couple bucks more.

    Fred.
  • wwest's avatar
    wwest
    Explorer
    Jun 26, 2014
    My best guess is that with a long period of non-use the compressor motor lubricant congeals just enough to prevent an initial COLD start.

    Puzzlement... You seem to be saying that the blower motor also shuts down when the compressor motor attempts that initial cold start,...True?

    Then I would suspect a poor/marginal electrical connection, start with the CB.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jun 26, 2014
    donn0128 wrote:
    Go up on the roof take the cover off and try spinningnthe motor by hand. Mine did that a few weeks back and a bit of WD40 on the motor front bearing cured the issue.


    How do you spin an A/C Unit compressor motor?
  • donn0128's avatar
    donn0128
    Explorer II
    Jun 26, 2014
    Go up on the roof take the cover off and try spinningnthe motor by hand. Mine did that a few weeks back and a bit of WD40 on the motor front bearing cured the issue.
  • Heisenberg's avatar
    Heisenberg
    Explorer
    Jun 26, 2014
    It will pay to change the capacitor out before you damage the windings. It is a cheap fix.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jun 26, 2014
    Sounds like compressor starting capacitor....cheap easy fix to find out

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