AC kills generator

Discussion in 'General RVing' started by SURVEYOR1, Jun 3, 2008.

  1. SURVEYOR1

    SURVEYOR1 New Member

    I installed an inline fuel pump to my Onan 2800 Microlite because it was acting erratically.
    It seems to run fine now and powers everything o.k. except the AC. When I flip the ac switch to cool it instantly kills the generator.
    The no-load voltage is right at 122. I read somewhere in the forum that it should be 128-130.
    Could this be the problem and if so, what's the fix ?
     
  2. Kirk

    Kirk Senior Member

    Re: AC kills generator

    On an Onan generator, the frequency and the voltage are both used in the control system and the no load voltage is higher than 120V but I don't think that it is quite as high as 128V. I can't find it in writing so may be off, but I think that it is more like 124 to 126V. At no load the frequency should be 63 Hz and under full load it should be 58 Hz, if I remember accurately.

    The Onan control circuitry detects a drop in voltage and then opens the throttle to bring the speed back up and so maintain the voltage. The adjustment is not an easy one and you do need to know what you are doing. With any luck there will be someone out there who has a service manual for one who will join in. If you should happen to locate a place to get a service manual for Onan gensets, but all means do let us know!
     
  3. hertig

    hertig Senior Member

    Re: AC kills generator

    if the generator is only 2.8KW, it might not have quite enough oomph to overcome the high startup current of an A/C which has not been used recently. I had a 3KW Honda which would not reliably start my A/C until I installed an 'easy start' kit in the A/C. This was a big capacitor and a relay, which gave it a little extra push when starting up the A/C.
     
  4. SURVEYOR1

    SURVEYOR1 New Member

    Re: AC kills generator

    Interesting.
    How hard was it to install this "easy start" kit and where do I get one ?
     
  5. Kirk

    Kirk Senior Member

    Re: AC kills generator

    Those kits should have instructions with them. Most RV shops will have one in stock but I'd make sure that it is intended for the air conditioner that I have.

    Your genset has a peak current of 23A and it can probably deal with slightly higher surge current. Hertig could be right about what the problem is, particularly if you have any other loads at the time the unit starts. Your a/c probably has a run current of about 13A to 15A and a start current that can surge to more than twice that amount.
     

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