[Richard]

Low current draw and freezing coils are classic tell tales of low charge. Those units typically do not have ports for measuring gas pressures. Almost all RV techs consider them to be disposable units. If you have a refrigeration buddy, ports can be added and the units recharged. However given the labor cost, the age of the units, and the exorbitant cost of R22 today, you may be better off with replacing the unit.