Having been an A/C tech for a number of years, I can offer this advice. You will be dealing with the low pressure side. When running, the pressure should read somewhere between 30 to 50 lbs. Buy a recharging kit that has a built-in pressure gauge. you will be using the 12 oz. cans of refrig 134. The recharge hose end will have a quick connect fitting. Connect to low pres. side and begin charging. The most cautious way to charge is to keep the can upright so as not to allow liquid ref. to enter system which can "slug" the compressor, causing valve damage. This will take a little time, you could need more than one can, no more than two. Have someone in the MH watching a dial thermometer stuck in an outlet grill. Have the A/C controls set to max air and recirculate. Depending on the temp. in the cab, you should end up with outlet temps somewhere between 45 to 55 degrees. This is the quick and dirty (cheap) way to recharge your engine driven A/C. The alternative is to take it to an automotive A/C shop, where they will evacuate the system, to check for leaks, and give themselves a starting point, then fill the system with the exact number of ounces of refrig. called for on the system specs., if they can find them. Take money.
Dudley Do Right, 2006AlpineApex40MDTS