Just made a relatively short trip - 165 miles - in ol' red, my  '88
vanagon. Took me 5 hours, the first 2 hours due to bumper to bumper traffic
for miles on the interstate. From 0 to 15 mph.  It was incredible! One
would have thought there was a wreck somewhere, but it was just holiday
traffic. And I thought it bad during the work week!

Anyway, I just brought my AC back to life by recharging with HFC152a,  and
the system performed admirably. The OAT at the time of travel was approx.
98F and the system kept the van comfortably cool in that slow traffic on
medium with high blower. Clearing the slow traffic I reset the blower to 2.
For the rest of the trip. Engine performance was flawless.

One question: with the AC running continually all that time,  the coolant
temp needle rose to where it just touched the upper side of the low coolant
warning light. Is that what would be expected?

John