Dometic Roof Air / Engel Fridge Freezer

[jelag]

OK so here's the scoop....


One of the roof air units(Dometic) on our motor home started to what I call short cycle.... run for 20 to 30 seconds, shut down, run for another 20 to 30 seconds and do this for as long as it was turned on.... the other AC works great.... So I shut down the one AC that wasn't working correctly....


A day later I restart the one AC and now the compressor starts, the fan starts and runs contiguously and no cold air.... I can hear the compressor start, run and the fan works.... I pull the cover and can touch the compressor and it seems to be working.....



Don't see any sign of Freon running with the cover off, and the usual frost is not there.....



QUESTION: IF the AC starts to run low on Freon will it short cycle for some reason....


NOW onto the Engel Fridge Freezer.... we've owned this almost 20 years...often runs on either 12 v. or 110 v AC for months at a time depending on what we are doing.... been really a great unit....



Now plugged into household power in the garage.... all of a sudden I walk by and its short cycling just like the roof unit on the motorhome.... I shut it down and power it back up a day later and now it runs continuously and the coils inside the unit no longer get cold... a close examination can't find anyplace where there might be a leak.....



So it seems like the same failure on both units.... I've done my homework and searched several forums where..... "its blowing warm air, replace it" etc... etc.... is there someone who understands these simple systems and their controls and can tell me what is really going on....


Of course both are either over 20 years old or close to it... yet both are sealed compressors like a modern refrigerator or freezer.... any thoughts....