Forum Discussion

mchero's avatar
mchero
Explorer
Aug 23, 2014

BOTH roof AC units running on a 20 amp power source?

I still can't figure out how this is happening! I had done this exact same procedure couple weeks back so I thought I would document the procedure.

I'm connected to a 20amp outlet in the garage., about a 30" heave gauge extension cord to the 50 amp cord.

Walking into the Discover I see the EMS system drawing about 7 amps. I shutdown the charger & I'm not at 5amps

set both AC units to cool with the fan on auto.

After a minute the #1 AC fires up & I see the amps spike to about 22 and then drop down to 10amps I hear the one compressor startup & the amps spike above 20amps for a second then drop down to 15 amps.

OK, I climb up on the roof, only rear compressor (AC#2) running) I climb back down, drop the thermostat on AC 1 to 70 deg.

Climb back on roof BOTH AC's fan AND compressor running. Back in coach BOTH AC's on & blowing cold EMS showing both AC's WITH compressors going drawing 17 amps. Looks like the EMS sheaded the HWH and Norcold fridge.

Thanks

39 Replies

Show More
  • time2roll's avatar
    time2roll
    Nomad
    Aug 23, 2014
    Must be new high efficiency scrolling compressors.
    I call good it to go :B
  • mchero's avatar
    mchero
    Explorer
    Aug 23, 2014
    Big Katuna wrote:
    One of the compressors isn't on. I have an 05 Fleetwood and I'm guessing we both have the Intellitec EMS. Did you select the 20A mode?

    Both ACs on is about 25-27A depending on the outside temp.


    Yes Intellitec EMS se on 20 AMP. with HWH & Fridge shed.

    Gee must be tripping on top of that TALL roof.

    As stated above, BOTH AC fans running, I hear BOTH AC compressors running, I feel each return line to the compressor, both are very cold. I then climb down the ladder, get into the coach and feel cold air blowing.

    Looks like I'll have to videotape it eh?

    I have been RV'ing for 10+ years in a 93 Pace Arrow diesel pusher with 50 amp service. Believe me, I know what I'm seeing.
  • mchero's avatar
    mchero
    Explorer
    Aug 23, 2014
    Let me add more to the information.
    50 amp power cord, 50 to 30 adapter, 20 to 15amp adapter to cord running to garage.

    "Have you got both AC units connected to the same leg of the 50 amp service? I thought they were normally split so each one is on a different hot leg, unless your units are done differently?"

    Let me add more to the information.
    50 amp power cord, 50 to 30 adapter, 20 to 15amp adapter to cord running to garage. It's the 50 to 30 amp adapter that connects both legs of the 50 amp service.
  • mchero's avatar
    mchero
    Explorer
    Aug 23, 2014
    Johno02 wrote:
    Leave it on for a while and see what burns up first.


    Well thought out comment, thanks for the mindless post.
  • myredracer's avatar
    myredracer
    Explorer II
    Aug 23, 2014
    I don't know how 2 AC units could possibly run together on a 20 amp supply, even ignoring any other loads that could be on. If you are reading 15 amps on one, that'd be 2x15 = 30 amps.

    Have you got both AC units connected to the same leg of the 50 amp service? I thought they were normally split so each one is on a different hot leg, unless your units are done differently?

    Do you have specs on the AC units that will show what the normal full load current draw is (at 120 volts)?

    Regardless, what voltages are you seeing?
  • Big_Katuna's avatar
    Big_Katuna
    Explorer II
    Aug 23, 2014
    One of the compressors isn't on. I have an 05 Fleetwood and I'm guessing we both have the Intellitec EMS. Did you select the 20A mode?

    Both ACs on is about 25-27A depending on the outside temp.
  • dougrainer's avatar
    dougrainer
    Nomad
    Aug 23, 2014
    Need more info. Model numbers and brand of the roof AC units. What is the outside ambient temp where you are at. There are some RVP AC units that are lo amp draw units, about 11 amps with fan AT 95 DEGREES AMBIENT. For each drop in temp of 10 degrees the compressor will pull 1 amp less. SO, if your ambient is 75 degrees, those AC units will pull 9 amps each. Doug
  • OpenRangePullen's avatar
    OpenRangePullen
    Explorer
    Aug 23, 2014
    Something somewhere is wrong, call an electrician. Their is now way 20amps can run 2 Air conditioners.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,344 PostsLatest Activity: Dec 26, 2025