Trouble-shooting is usually a matter of isolating things one at a time to find the culprit.
Yes you can have a loose connection someplace. First take out each AC circuit breaker and tighten the black wire into it at the set-screw and replace it on the buss firmly.
There are more steps, but take one at a time here, after you report in on that much.
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.