Coach power problems

I agree with the person who said "Generator Problem" but disagree as to the specific.. What you describe "Reving up and slowing back down, Reving up and slowing back down" is called HUNTING and it indicates a too rich fuel air mixture on a governor controlled engine. (This is what I get for being trained in small engine work) too lean causes misfire by the way. Now I'm not saying that is the only possible cause, but if you have something like a Progressive Dynamics HW-50C installed post-Transfer switch, it will lock you out when the Generator is doing that.

you need a tune up.(An old fashion one) or, perhaps, a new air filter. or (most likely) BOTH.

In your post, you say when the roof airs, as in plural. What happens when you just add the load of ONE A/C?

The load of starting an A/C is quite a lot higher than when running. This is particularly true if a capacitor in the A/C is bad.

If both are starting at the same time, the generator may not be able to catch up quickly enough.

Maybe your generator is asking for more fuel to pull the extra load and there is an obstruction (think fuel filter).

"jtad".....You can try a couple of things. First, try it with one A/C. This will eliminate an A/C unit going bad and drawing too many amps. If that's not the problem, turn off your battery charger. I'm not familiar with the Zantrex, but on the Magnum inverters, there is a button to shut down charging. Lastly, if you have the inverter on while running the A/C's, shut the inverter off. This will be the easiest way to make sure something in the coach is not drawing a big load before jumping into generator issues.

jtad wrote:
Could a bad house batt cause this?

Bad batteries can contribute to all sorts of problems. Always good to rule that out first.

Could a bad house batt cause this?

jtad wrote:
It shows I'm drawing about 8 amps with both roof air units off...

Assuming everything else if off, that's almost 1000 watts, which indicates your charger is working hard.

When I had this problem with my Prosine 2.0, I changed the "Ac breaker size" parameter (in the control panel) which dialed down the amount of amps going to the batteries.

See if that helps.

That said, a generator that big should be able to handle it just fine. Anyway, it's worth a try. I don't know how big Onans handle surges.

There can be several things causing this. The good news it the genny knows a heavier draw is coming and kicks in. The easiest thing up front I'd suggest is make sure all tune ups are done to the genny. Make sure your plugs are good, your oil is clean, and air filter is clean. Put some marvel mystery oil in the fuel. Remember when a generator has a heavier load, the engine is under more strain. I'm not saying this is the cause, but it is always a good place to start diagnosing for minimal costs (plus it's good for the genny)

No when I'm saying the power comes back on it is coming from the generator. I can see it on my remote display. It shows I'm drawing about 8 amps with both roof air units off.. As soon as you kick the roof airs on and they start to draw a big load it kills all power from the geni.. The airs kick off, then a couple seconds later the power comes back to the coach (from the geni) Airs try to start again, power shuts off.. And it just keeps cycling like that.. Then generator will idle up as soon as it senses the pull from the AC's but then the power is killed and it idles back down.. If left alone this cycle will happen about every 15-20 seconds.. Turn both airs off and power comes back to the coach from the geni. Its almost like your flipping the transfer switch on and off if that makes sense. Bill I've not tried it with just one air yet.. It is an Onan 7500 diesel. I was thinking this morning that maybe both compressors tried to hit at the same time and it sent it into some shut down mode and was sheading power..

How does it run with only 1 a/c unit running? What size generator are you using?