I have heard that the
rear AC systems on Chrysler minivans
are troublesome.

Are there specific spots in the AC lines prone to leaks on 2001-2006 models?

2005 Town & Country extended 3.3L
With rear AC system option with a factory fill of 38 oz 134a.

AC worked flawless from 2005 to about
3 weeks ago when air out vents seemed warmer than normal.

Checked low side pressure and found
25 psi when outside air temperature was 86F

Added 12 oz of new 134a with UV dye to the
38 oz system initial fill from underhood label.

Low side pressure came up to 47 psi
and air from center dash vents with recirculate on
dropped down to 48F

I shined a pretty bright UV flashlight around and did not spot any large dye marks in the engine compartment but small old looking UV glow spot near dryer.

This afternoon air from dash seemed warm again.

Low side pressure had dropped back to 12 psi with outside air at 83F.
Air out dash vents was 59 F.

Added 12 more oz 134a and low side pressure increased to 35 psi.
Air temp from dash vents dropped to 54F.

The fins on the lower side of the condensor look pretty beat up from bug and road debris hits. Chrysler did not put a grille screen there.

I may be imagining things but when the van is first started up
the air first out the vents does not smell moldy,
but it smells "different" to me....

Can a 9 mm camera head diameter video boroscope probe be threaded in to inspect the evaporator through any of the dash vents or maybe recirculate air opening?

Most common .
Condenser or front evaporator.

Ive never had to replace a rear evap unless it was in an accident

Rear evaporator very common. They are partly exposed behind right rear wheel. It collects all kinds of gunk from road & corrodes the aluminum. I changed mine on my 07 in 2015 and the one i took out had a production year of 2008 so it had already been replaced once. I also changed receiver-dryer. 15 bucks @ Napa. I bought evaporator & expansion valve from Falls motor city on eBay for approx half cost

almost always when you "smell" something inside the vehicle, it is time for an evaporator. if it's the front one, put in a heater core while you are in there, as it's a real "fun" job to get there, and i really don't think you would want to do it twice. the heater cores are cheap enough. just my opinion.

Is there an on vehicle test
to rule out leaking compressor shaft seals?

Should an AC system get 2 oz of compressor oil every 5 years to extend the life of the seals, or are modern compressors good for their practical lifetime after the factory fill?

A bought new 1983 T-Birds AC compressor seals failed after 10 years.
Is 134a harder or easier on compressors or their oil than the old R-12 ?