Brand new rv 13.5btu AC issue

[pkhjr]

I have a brand new Winnebago Micro Minnie with a 13.5 btu AC that runs fine but my 3400watt generator won't start it, goes to fault every time with nothing else going. I confirmed my gen to be good by starting a friends 15.0 AC with no problems. His RV was pulling 4 amps before we tried the AC so its not the generator.

So I climb up on my unit and check the start capacitor. The compressor side shows to be good. The fan side no capacitance. Ohm meter shows dead short. I'll replace the start cap but do you think that will solve the problem? It seems the fan side is so small compared to the compressor side.

Thanks Tex

[Spridle]

I had the same problem. I installed a Supco hard start capacitor that worked until it got close to 90 degrees then it was back to my generator tripping. Man was I frustrated, I was about to buy a 7000 watt Honda out of frustration. Instead I bought a Micro-air soft start for $299 and $40 dollars off using a discount code I found on the web in some boating forum. I installed it last week and it worked without issue from that point forward. My Yamaha 2400IS barely changes sound when the condenser cycles on. That's one in the win column.

[wa8yxm]

I agree it is hard to test a Cap with an Ohmmeter..

First. It takes time. and you have to know both the value of the cap and some things about your meter.

When you first connect the leads it will (or should) show DEAD SHORT for a capacitor that is "discharged" is a DEAD SHORT when power is first applied

THen as the cap charges resistance should go up ideally approaching infinity (In practice for large electrolytic caps like the ones under discussion it won't go that high) The value of the cap and some meter stuff indicate how fast it rises

The value of the cap can be determined by how fast it rises in fact.
Today I have Multi-Meters that measure Capacitance.

In the old days I did it with a Vacuum Tube Volt Meter and a stop watch.

[dougrainer]

pkhjr wrote:
Works fine on shore power. Unit is Dometic 13.5k btu. A new AC should not need hard start. I'll replace the current start cap and see what happens. My gen is more than enough to start the Dometic.

Well, that is where you are wrong. Depending on the AC and the Genset, you need a Hard Start kit. RVP options Hard Start kits for the OEM when they install smaller Gensets on Towables. Dometic does not. IF your unit runs OK on Shore Power but not on your Genset, it is NOT the AC and its capacitors. Your Genset is not capable of the surge current needed without a Hard Start kit. Doug

[time2roll]

Are you saying you are using old start caps with a new air conditioner?
I would have all new.

https://www.microair.net/collections/easystart-soft-starters

[1320Fastback]

I broke out a old Onan BFA that I have for emergency power today. It is 33.3 Amps vs the 26 Amps that the twin Yamahas have and it ran my Dometic 13.5k with no issues.

Atwood Ac here I come!

[pkhjr]

Works fine on shore power. Unit is Dometic 13.5k btu. A new AC should not need hard start. I'll replace the current start cap and see what happens. My gen is more than enough to start the Dometic.

[dougrainer]

1. Does the AC work on shore power?
2. Is your AC a RVP(Coleman) unit?
3. IF it works on shore power but not from your Genset, then add a HARD START kit to the AC unit and your problem should go away. You can get the kit from RVP or your local AC supply. Doug

[pkhjr]

Guess fault is not the correct term. Gen goes to overload. I stated nothing else running. I threw the breakers for everything but the AC. I have determined the start cap is dead on the fan side. Just asking if that is enough to overload the gen. Regardless the start cap will be replaced.

[TomG2]

pkhjr wrote:
.... my 3400watt generator won't start it, goes to fault every time with nothing else going. .......

I have to ask, what do you mean by "Goes to fault"? Like a gfci kicking out or a true overload condition? Just asking.

Nine out of ten people that post similar posts come back and report everything it okay but they forgot about the converter, refrigerator, water heater, crock pot, etc. running the background.

[1492]

[pkhjr]

I checked the start cap with a capacitance meter before I ohmed the fan side.

[1320Fastback]

Ive had it with our new Dometic AC. It consistently fails to run on twin Yamahas and even bogs down on shore power.

Its getting thrown in the trash soon for a new Atwood, which Dometic now owns but hopefully they have kept their hands off it.

[ScottG]

It's hard to check a cap with a DVM. The DVM charges it and you get odd readings.
If you discharge the cap and then take an initial ohms reading, you should see the value keep changing.
If the intial, discharged reading show a dead short, you've got your man!
I wouldn't worry about the sizing of the components. They are sized to deliver the rated BTU.