We do the 15/20A house receptacle here all the time for our 13,5000 air conditioners. They are connected to the RV30A-15A adapter first then a 10-gauge 50-foot extension cord goes from there to the garage. Be sure your 30A to 15A adapter is one of those long 'dogbone' type adapters (WALMART) and not one of those small round types.
Should look like this
They do just fine here...
After you run your for a few minutes then walk outside and feel all of the connections. You should not have anything starting to get WARM on you...
I also have one of these RV120VAC meters plugged into the a receptacle inside the the trailer where I can get a good glance at it.
These meters have the GREEN SAFE ZONE printed on the meterpanel. If the 120VCA is within this green safe zone then it is OK to run the air conditioner. When we first turn ours ON they usually jump below the SAFE ZONE until the A/C starts then stays inside the safe zone.
I found a couple of good 10-gauge (10-3) heavy duty contractor grade 50-foot extension cords from a garage sale. You can get by with a 12-gauge (12-3) size but those red orange looking extension cords from WALMART are to small a gauge to use. They will get hot and burn your up things perhaps even your a/c compressor...
Air conditioners in the RV trailers are not known to get ice cold anyway. I wouldn't expect them to perform like they do in your house with thick walls and well insulated attics etc... Try to park in the shade if you can...
Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS