power and my air conditioners

[modell]

This weekend when it was hot as blazes in virginia, we were in a campsite and I had the old Suncruiser plugged into the campsite shore power. I had both air conditioners turned to auto, but only teh front unit would run. The back bedroom unit relay would click if I changed the thermostat, but it wouldn't come on. If I turned on teh geerator I could run both units, no problem. So, obviously it was a power thing.

A friend I was with told me I could get a pig tail to put on my shore power that wouls allow me to connect to teh 50amp service as opposed the to the 30amp service. I was concerned that I may cause real harm to the electrical system in my coach if I did this.

Anyone familiar to this? I don't believe my genset is a 50amp. It says 40amp on teh tag on it. But it's confusing for me.

So was there something wrong with the power feed this weekend making the 2nd A/C unit not run or do I need more than 30amps juice to run both units?

Thanks!
Matt.

 

[Tom]

Matt,

If you have 30A service in your RV, it won't run two a/c units from shore power, although they will likely run from the 40A generator. There will be a switch or relay that prevents you from running both on shore power. Even if you rig an adapter and plug into 50A, it won't change the way your RV is wired.

We have an article in our library contributed by Winnebago's Engineering Staff called 30A vs 50A service. It's a little dated, but is nevertheless factual.

 

[modell]

Ok Thanks. I just have a little confusion still.

I have a switch that allows me to select front & back A/C units or rear A/C unit. With the generator I have no problem running both units. So are you saying that 30amps is not enough power to run both and that my genset must have more than 30amps to be able to run them?

I'm just trying to clarify. Thanks so much for your help.

Matt.

 

[Tom]

So are you saying that 30amps is not enough power to run both and that my genset must have more than 30amps to be able to run them?

That's it in a nutshell Matt.

BTW while you were posting your reply I edited my prior message to add a link to an article in our library. You might not have seen it.

 

[modell]

Oh, and thanks for the URL too. Very interesting.

 

[cuts_up]

This sounds like a good place to ask my a/c question.  We have a 30amp mh.  Until last month with the switch in the front position both a/c's ran with generator power.  They were both running, then the rear a/c stopped.  Now we can only run the rear a/c with the switch in the rear position.  The first thing that came to mind was that the breaker on the generator flipped, but it was in the "on" position.  We were enroute when the rear air stopped and we were pretty worried about keeping cool while sleeping at our destination, but when we set the switch to rear the rear air ran fine.  So front and rear units both work, just not at the same time anymore.

My question is, do those selector switches go bad?  What else could cause this problem?

 

[Tom]

The selector switch in the example I gave is usually only in the shore power circuit and should have no effect on running from the generator. The second a/c unit would normally be hard wired to the generator, bypassing the switch.

Sounds like a problem for one of our techies to figure out.

 

[modell]

Could the issue be directly at the generator? When I read the article that Tom gave me the URL for earlier in this thread, it mentioned that the bedroom unit had it's own 20amp breaker on the generator. I have noticed that is how mine is setup. Maybe that needs to be reset at the generator.

Just a thought.

Matt

 

[Gary RV_Wizard]

Yes, the problem is likely at the generator, in the circuit breaker for the rear a/c (typically a 20A breaker). Either that or a wire from the generator to the rear a/c has broken somehow.

The Front/Rear switch is still active when the generator runs and should be in the Front position. By switching it to Rear, the rear a/c has been transferred from the direct generator power circuit to the regular 30A power power, which is coming from the genset's 30A breaker. That's why the rear a/c runs and the front does not in that mode - the rear a/c has replaced the front a/c on the 30A supply.

In essence, the generators 30A breaker is supplying the same power as shore power and doing it via the same wiring in the RV. The generator 20 amp breaker is dedicated to the rear ac/ in most all 30A power RVs.

 

[Clay L]

My 2004 30 amp Winnebago Sightseer does not have an automatic transfer switch for shore power to generator.
The power cord must be plugged into an outlet in the service bay when the generator is used and there is a switch near the ac and dc circuit breakers that must be in the "Generator"  position so the rear AC will operate.

On shore power it must be in the "Powercord" position for the rear AC to operate.
Both ACs will run at the same time on either shore power or generator.

On shore power the energy management system will not let the rear AC start at the same time the front AC is starting because of the high start up current required, but will allow them to both run at the same time.

On generator power they can both start and run at the same time.