What size A/C does your Pop-up (PuP) have? A small A/C should work on the 15Amp circuit. Look up the model and make sure. The reason is, many RV Air Conditioners are made with an overload circuit, which if you try to run it with too little power, it will blow. If it is under warranty, it will void the warranty. If not, then you'll just need to replace that fusable line.
We had a small unit on our PuP (Mach 10), which is rated at 13 Amps, so it worked fine on the 15 Amp circuit.
Just letting you know.
By the way, there are lots of cool things for Pop-ups at the popupportal.com. Excellent location for PuP-specific stuff. We used that quite a bit, when we had ours.
Ben and Doreen
Home Away From Home - 2017 PT Crusader 315RST
TV - 2008 F250 Lariat 4X4 6.4 Diesel
42 nights camping in 2015
61 nights in 2016 (still not enough!)