13.5 vs 15K BTU A/C power requirement

Mark S · 06-27-2014, 04:48 AM

I own a Dometic 3,000 watt inverter generator that is advertised to run a 13.5 BTU Dometic a/c. I used it only a couple of times on my old camper and it worked ok.

My new XT 267 has a Dometic 15,000 BTU a/c. We stay at campgrounds but occasionally I would like to be able take a rest area break and have a/c for a little while.

Does the 15K BTU a/c take more power to start than the 13.5? Before I hook up the generator to try, I am wondering if it does not have enough power will it damage the a/c unit. Which breaker will trip first, generator or A/C?

Thanks

looking4fun · 06-27-2014, 02:17 PM

My guess would be the breaker in the camper for the a/c would trip first. I say this because my 189fbd has a 20 amp breaker for the a/c circuit and the generator I have I believe has 30 amp breaker for the twist lock plug. Lower amp breaker should trip first. But also my generator is a 4000 watt not a 3000, idk if that would make a big difference.

Mark S · 06-27-2014, 04:13 PM

I tried it today and the generator died each time I put it under a load from a/c or microwave. It ran fans ok but something is wrong.
I'm going to take it in tomorrow to get it checked out.

profdant139 · 06-28-2014, 01:10 PM

If the generator runs fine but dies when you hook it to the a/c, there is probably nothing wrong with the generator -- just too much load. Does the generator run rough at idle?

Mark S · 06-28-2014, 04:02 PM

I tried fooling with the generator today. I put new gas in and yes it started but was running bad and stalled after a few minutes. It has been sitting for a long while. I started adjusting the carborator and then decided to take it in to the place I bought it. I do pretty good working on carbs, but it's the problematic extra parts when I rebuild that is the problem.

profdant139 · 06-30-2014, 10:38 AM

Mark, do some searches on rv.net -- there is lots of good guidance on how to maintain a generator. It took me a long time and a lot of money before I was finally persuaded to do it right -- drain the carb before storage, add Seafoam to the fuel, use good gas, run it hard at least once a month, and so on. Kind of a hassle, but the carb is very hard to keep clean.

Mark S · 07-06-2014, 06:01 PM

Turns out the paper in the fuel filter broke down and clogged the gas flow. Picking up generator from shop tomorrow. I can't help but think ethanol played a role in this.

profdant139 · 07-07-2014, 10:27 AM

Mark, that is very discouraging -- my service tech showed me how to drain the carb when putting the generator away for storage, but I am now wondering whether that is enough -- does draining the carb also drain the gas out of the filter?

I wonder if they make more durable fuel filters.

Keep us posted on how it is going!

Mark S · 07-07-2014, 03:06 PM

I got my generator back from the shop today. They installed the fuel filter they use on Onan generators. It seems to run well now.

I don't have ethanol free gas readily available but I always used either Stabil for ethanol or Startron gas treatment.

It trips when it tries to start my 15,000 btu unit.

It will run several fans and the microwave or coffee maker and a leaf blower at the same time with no problem, just no AC. I guess I could try a hard start capacitor but I don't have time before I leave on Saturday. Oh well.

profdant139 · 07-07-2014, 10:24 PM

I am sure you thought of this, but have you turned absolutely everything else off before trying to run the a/c? The initial surge is very high, and then it settles down after the a/c starts. I wonder if there is a way to rev up the generator for a moment, maybe with a quick flip of the choke?