The rear heater core is prone to failure more so than the front. Have it inspected and replaced if needed. A small amount of coolant can make a lot of vapor. Also, I would only open the valve part way. Coolant that flows to the rear heater is not available for the front heater and it needs all it can get since it is heating outside air. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Eric Caron
Sent: Sunday, November 23, 2014 10:07 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Smelling coolant suspect rear heater

        Hi folks,

        I’ve been out with the van a few times in November and have turned the rear heater valve back to full and have been using the rear heat.  I smell coolant when I turn on the rear fan.  I don’t smell it when the fan is off.  I have not found any coolant on the floor under the seat.  i do have the drain plugs open as a prevention in case of leak.
has anyone noticed this smell before a rear heater failure?  could it be the fan rather then the heater.  When I purchased the van the rear heater fan did not work but replacing the fuse has fixed the problem for over a year.

coolant level is unchanged.

Experiences,and recommendations appreciated.  I’m considering just calling a vendor to change out the core but it seems silly to do if it has nothing to do with the heater core.

Eric Caron 
85 GL Auto