This wire is a dedicated feed directly to the alternator. My hunch is that it was not reconnected after the engine install. Look for it on the left side of the engine compartment.  If is is connected it could be the crimp connections are burned out. If the wire does need to be replaced use a #8.

Dennis,
From my phone.
________________________________
From: John Rodgers<mailto:jrodgers113@GMAIL.COM>
Sent: �5/�17/�2017 7:03 PM
To: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM>
Subject: Air Conditioning - 1991 Carat - HELP!

Have worked over this AC. The one fault I have found is there is a failure
for power to get from the Alternator B+ to the feed side of the 50 amp
fuseable link which protects the AC system. This wire circuit is shown in
Bentley page 97.144! I jumpered past this to get power an the AC Ran
sucessfully, so I'm confident that circuitbin BENTLEY is the one at fault.
Would appreciate any suggestions or clmments as to how to deal with this.
That wire is buried inside the engine harness!

Thanks!

John
Proud but AC frustrated Carat owner!!!