No AC unless 30 amps

My guess is too thin and too long of extension cord causing voltage drop when the air conditioner comes on, then there may be an EMS system that shuts it down on low voltage to save the air conditioner from burning out.

A better solution would be a 30 amp rated extension cord with the 30 amp to 15 amp dogbone located near the outlet. Don't use one of those 30 to 15 puck adapters running an air conditioner as they tend to overheat.

p.s. that 30 to 50 amp dogbone in the middle only draws power from one side of the 50 amp plug. So no power is coming through that second extension cord.

What do you mean by “run for a few minutes only”? Does it trip a breaker?

If he is attempting to plug into two 20A outlets that are next to each other, he is still plugging into a 20A breaker. Likely any outlets in his garage or outside will alp be on a single 20A breaker. So, he wasted his money. 13.5K BTU AC will have a locked or starting rotor draw of around 3000 watts. Add in the converter drawing XX amps, the refer drawing 600 watts and its no wonder it trips.

beaubeau wrote:
Posting for a friend ...
She has a new Jayco Melbourne. It’s on a Sprinter chassis.
Her AC works fine if she’s plugged into a 30 amp circuit (her RV doesn’t have a 50 amp plug).
But plugged into 20 amp it will run for a few minutes only.
So her husband bought a splitter from camping world meant to plug into to 2 110 outlets and combine them into 30 amps.
Same problem.
Any ideas?
This is what the splitter looks like in use

If both are plugged into the same circuit, it won't make a difference.

With the extra adapter I assume the splitter is 2x 30a to 50 amp. This will not combine power. Actually you are drawing power from only one side of the 50a and likewise from only one cord.

I don't think amps is the issue as much as voltage. Those extension cords look a bit thin and maybe too long. Red cord is maybe OK but should be #12 wire minimum. Check and monitor voltage in the RV. You are looking for 108+ when running. Post your findings.

An air conditioner should work fine on a 20 amp circuit unless it's a GFCI protected circuit or something is wrong with the air conditioner or other things are also running on the same circuit.