I did find that fitting after looking for a bit.
Thanks.
I did the low side test a bit more correctly this time, revving the engine to 1500 rpm, and I was a bit below 25 psi on the low side, maybe 20 psi.
I was getting 64 degrees out of the center vent. At idle I was only about 34 psi, so maybe I have a leak?
Revving and adding a bit at at time I finally got the low side pressure up to 26 psi and that was the end of the 12 oz can.
Center vent temps are now at 60 deg F.
Not great, but better than the 110 deg that it gets to sitting in the sun all afternoon.
Harbor Freight won't have my guages til Friday so I won't get to do much more for a couple of days...

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Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic