I have a 98 Suburban with the 350. The canister on the AC lines are mufflers - that's according to my neighbor who is the lead tech at the GM dealer.

The front evap discharges into the accumulator because of the orifice tube. I think this site does a good job explaining the difference between the receiver/drier and the accumulator.
https://macsworldwide.wordpress.com/2010/07/13/three-important-functions-of-the-receiverdrier-in-your-cars-ac-system/

It's hard to make a guess about what the issue(s) could be. I would probably start with putting on a set of gauges before the problem started to establish a base-line, drive it around until the front AC quits, then put the gauges back on.

Are you 100% sure there is no issue with the blend door?