Don't understand my air conditioner

It sounds like the fan was running and blowing ambient air. I have Coleman Mach 15's on my coach and more than once I have has the same thing happen. It seems to happen when very hot outside (110+), dry, and the coach is hot inside (90+). I have full air flow out the vents so it is not icing up. If I turn off the unit for a minute then back on it will works fine. I think the compressor is overheating and shuts off. It won't come back on without shutting it off and back on. I also notice that if I do not allow the inside temp to get above 85 of so it will stay running even at 115 outside.
In your case the 15amp extension cord could be overloaded causing a low voltage issue too.