Hey Jim-
On residential units, if (with the unit turned on; i.e., the compressor running but the fan not) you have to spin the fan by hand to make it run......it is almost always the fan capacitor. (Capacitor is "open".) Same should be true, I believe, for an RV A/C or Heat Pump unit.....but I have never worked on them. These days, the fan cap is usually in the same "can" as the compressor run cap, so you will probably need to buy the whole thing (somewhere around $25). If the fan cap is separate, it will be much smaller than the compressor run cap. Suggest you mark the wires, remove the cap and take it to Grainger's or equivalent for a replacement part.
I have a capacitor checker, but they are too pricey for the average guy to keep in their tool box (and take up space). Perhaps your Grainger-type place could check the capacitor out for you...dunno. Unfortunately, most A/C supply houses won't normally sell to the public.....I know mine won't.
Good luck with the fix..............
