I plugged the motorhome into shore power. Naturally of course the A/C unit is not putting out cold air. The rear one won't even come on. Even though the switches are set to front so that they both...
Actually the rear ac unit is much more likely to be a blown start capacitor not a locked up compressor. Recharging the front unit or attempting it is a waste of time. If its low, the Freon went somewhere and will again. These are sealed systems. If its not low, adding the fittings is a waste of time and adds a likely leak point.
Sorry but if you are not DIY handy, you bought into the wrong RV. If you are, try replacing the start capacitor on the rear unit before giving up on it.