Forum Discussion

rockwind1's avatar
rockwind1
Explorer II
Apr 30, 2014

hard start capacitor supco spp6E or spp6 ac unit revisited

I am going to do this mod on my ac's and i have read a ton of different forum discussions. but most are from 2-5 years ago and there are still some unanswered questions. hoping someone on here has gone down this path before and can help

most people say use the spp6E but when i look it up, there are 3 different choices, all with different uf ratings, i bought the 1/2 hp to 3 hp one,,,88uf-106uf,
however, why not buy the size up with 130uf-156ufs? is this too much for the unit?

i have 2 units, one a 15k and the other a 13,500

also, the volt range on the spp6E is from 170 to 277, obviously my ac unit is 120 volts. does this make a difference?

they also now offer a spp6TD with a break on delay built into it, which seems nice.

the smaller spp6 seems to be rated from 120 to 288 vac.

which one is the question?

are rv air conditions

my ac's draw about 24amps and 21 amps for the start, then drop down to 8-11 amps running in 75 degree weather.

what sort of starting amp drop will i see?

thanks for looking at my post and for any help, kevin
  • mosseater's avatar
    mosseater
    Explorer II
    May 02, 2014
    I followed the advice of Supco's tech support in both buying and installing the supposedly correct model capacitor. After conferring with their tech support and connecting it two different way per their suggestion, my amp draw actually went up slighly and for a longer period at start up. Now, admittedly, it's difficult to get an accurate measure, but using an Amprobe analogue clamp meter and trying multiple measurements using a stop watch, I am convinced the hard start capacitor actually sent me in the wrong direction. Luckily, it's not expensive, so I was only out about $12 and an hour or so. Anybody wants it, shoot me a pm and we can work something out for cheap.
  • Larryect's avatar
    Larryect
    Explorer
    May 01, 2014
    Chris,

    I know from your posts, you are very knowledgeable on all things AC.

    It looks like the "E" type is now rated down to 90 volts from the picture. Based on that, I would agree it would be an appropriate choice.

    When I installed the non-E in my unit, Suppco was not listing the E unit down to that voltage level. The one I installed did help start-up. It was in-fact a larger capacity capacitor than the stock one it replaced. This was on a 1999 Dometic unit.

    Rockwind - I would recommend trying the "E" if the capacitance is larger than your stock unit.
  • Chris_Bryant's avatar
    Chris_Bryant
    Explorer II
    May 01, 2014
    The SPP6 (o E) is identical to the factory start kit- you will gain ZERO advantage if you already have a start kit installed. Supco has xchanged their mind about the E type- a picture of the last one I installed:

    The comments by Mr Berry are not logical- while saying the E type will not work for 120 volts (which would mean the relay doesn't get enough voltage to disengage), yet the ramp up time is too short.

    Quite frankly, Supco has made so many incorrect and contradictory assertions that I have stopped using, or recommending their product for RV use. If you want to run on a generator, use the factory potential relay with start capacitor.
  • rockwind1's avatar
    rockwind1
    Explorer II
    May 01, 2014
    after further research and reading the 158 comments on the link below, it would appear that the NON "E" SPP6 is the way to go. i am guessing that most folks who have good results with the spp6e are maybe mostly on shore power but i could be wrong.

    http://www.modmyrv.com/2009/05/27/rv-air-conditioner-hard-start-capacitor

    thanks to all who responded.

    i am going to start another thread with a fan delay question.
  • bob213's avatar
    bob213
    Explorer
    Apr 30, 2014
    Many opinions... I went the mfg. recommendation. Here's a letter posted on Rv Upgrades:
    1. Jim Berry (July 13th, 2011 at 7:22 am)
    If you are adding a hardstart to your RV A/C unit, use the SPP6 (no E). The SPP6E is not designed for 120VAC applications, The “E” series is also an instant restart unit, this does not allow the generator sufficient time to rampup to full power. The SPP6 has the preferred PTC relay and allows a longer ramp up time. The SPP6 is rated for 120VAC usage.
    Remember for every thousand feet above sea level you generator drops 3% of output. On hotter days the A/C drops in efficiency as well. Check with your A/C manufacturer on the correct generator size for your unit. As far as I know there is not a manufacturer that will reccomend a 2000 watt generator to run a 13,500 BTU A/C unit.
    If you have any questions about the SPP6 or any other Supco part, please contact us at 1-800-333-9125 ext. 261 our Tech Support will be glad to assist you.
    Thanks,
    Jim Berry
    Director Product Management
    Sealed Unit Parts Co., Inc.
  • rockwind1's avatar
    rockwind1
    Explorer II
    Apr 30, 2014
    another odd question, looking at the instructions for the spp6E, it say for CISR motors to hook it straight to the compressor, yet EVERYONE on all these forums say to hook it up to the run capicitor.

    perhaps i am wrong, i read that almost all rv ac units were NOT the PSC type but were the CISR type, does anyone know for sure?

    altern, could you be more specific? are you saying that the sp66e will open/work just fine with the 110 vac?
  • Altern's avatar
    Altern
    Explorer
    Apr 30, 2014
    Mr Wizard is correct.
    As for voltage both are in the range.
    For microfarad (uf), IFRC it should be within 10%.
  • MrWizard's avatar
    MrWizard
    Moderator
    Apr 30, 2014
    Your meter can't read the real startup load, it's not fast enough
    If you look on the compressor, very likely you will see an LRA of about 50 amps
    Lock Rotor Amps, this is the true high pressure restart value

    It's unlikely you will see much drop off the startup load on your meter
    What you will notice is less lugging of the generator when the compressor starts
  • Larryect's avatar
    Larryect
    Explorer
    Apr 30, 2014
    I am not fully up on this currently. But, I added the spp6 (no "E") to my 13,5 AC. I chose that one after reading the voltage ratings and how it worked about the E on the manufacturers web site. It seemed to me you may never reach the proper voltage to open the capaicitor using the "E".

    The one I added, made it easier to start with my 2400 genny.

    Others swear by the "E". Sorry, I don't remember the ampeage readings and I no longer have that trailer. I also added a fan start time delay to shift the fan motor starting load.

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