Brand new RV AC issues - help please?

[PharmaDoc]

New 2021 Reflection 150 295RL. Just brought it home from the dealer. Have 2 Coleman-Mach 48000 Rooftop AC units. No Easy-Starts yet.
Had it professionally inspected - on 50A shore power both AC's worked fine, cooled rapidly no issues.

At my house I did not install 50A service as the electrician said it would be very expensive due to wire run costs - he is an RV 5er owner himself and assured me that 30A service would be fine to run one AC unit without problems. Pedestal reads 116V on voltmeter, no polarity issues.

Have connected pedestal to the RV with both a 50A cord with a 30A dogbone adapter and also with only a 30A cord with a locking plug adapter. Same issues occur with each.

When I turn on the main AC, it starts fine, seems to start cooling, and after 60 - 90 seconds starts making a "grunting" sound or possibly some sort of cycling. I have to turn it off to make it stop, and it trips no breakers.
The bedroom AC starts fine (main AC is off), seems to start to cool, and after 30 - 45 seconds it trips the breaker at the panel.

Nothing else is running - microwave is plugged in showing a time. Lights off. Refrigerator off. No other loads I can think of except possibly the converter.

Would renting a 50A generator be of benefit to prove they both still work?

I am out of ideas at this point, any ideas or direction where to look would be extremely appreciated.

[huntr70]

Do you have a voltmeter to plug into an outlet in the RV to see what the RV is actually getting?

[PharmaDoc]

117.3 to 117.5 at multiple outlets.

[huntr70]

How about when you start the a/c?

What does it drop to?

[PharmaDoc]

as the AC seems to "surge" or cycle it is shifting between 109-110VAC to 115VAC.

[Heavysledz]

I have the same setup at home and my AC runs fine on 30A shore power but I have different model AC units than you. If I were you, I would look for the specifications for your particular AC unit and it will tell you the nominal load and the starting load values so you will be able to see if a 30A supply is sufficient. Personally, I have never seen an A/C that required more than a 30A hookup to operate. The only time I had issues was when I used an extension cord and due to the line loss, it wouldn't operate. I moved the trailer so that I didn't need such a long run and the issue never returned.

Remember, you only have a total of 30A shared across both legs of your 50A system. So make sure you have anything that draws any amount of load off when turning on the AC (i.e. electric HW heater, Fridge, Microwave....). Most people forget to realize that the converter typically includes a charger as well and if the batteries are not fully charged, it will draw upwards of 30-50Amps while charging. Granted this only equates to about 3-5amps of AC but it all adds up!

[Redapple63]

as the AC seems to "surge" or cycle it is shifting between 109-110VAC to 115VAC.

You are definitely bordering on low. Standards say 114 is officially low voltage, but around 110 things start acting weird.

I would try a different electrical source and see if you get the same voltages.

Not sure of your setup or how far from the plug, but if it is far you may be facing line loss due to distance, but it’s just a guess without more to go on.

Definitely low voltage situation, in my opinion.

[PharmaDoc]

Setup is 30Amp service on separate breaker in house. Connected with 25' cord, whether 30Amp or 50Amp with 30A adapter.
As I understand it, 50Amp RV service is simply 2 30Amp legs and the internal wiring feeds off individual legs - would 50Amp service make a difference?

Short of a generator, any way to rectify?

How do you handle this in a park with crappy power?

[Redapple63]

Setup is 30Amp service on separate breaker in house. Connected with 25' cord, whether 30Amp or 50Amp with 30A adapter.
As I understand it, 50Amp RV service is simply 2 30Amp legs and the internal wiring feeds off individual legs - would 50Amp service make a difference?

Short of a generator, any way to rectify?

How do you handle this in a park with crappy power?

Hi doc,

It is actually 2 50 amp legs. You should be good to run 1 ac on 30 amps. It seems more about the voltage your electric connection is providing. 109 is definitely low and electrical devices will act weird or not operate at all in these conditions. If you have access to a generator give it a shot.

Let us know how things go. I am sure people with more experience will chime in.

[BobLandry]

My Dometic Marine stuff is good down to 107VAC. Below that, not so good. One unit should run fine on a 30A service. A gazillion 30A rigs do it every day.
You are getting a voltage drop at the AC caused by either a faulty wiring job, too long a cord run from the pedestal, or a cord that is too small in sie, causing the drop.