I sympathize with you on this issue, only it has been sub zero here lately.  My 87 Syncro GL has been less than generous with the heat making for a cold ride to work and even colder one home.  As Mark Drillock has already suggested start with replacing the thermostat and see how that helps.  I am going to do mine this weekend now that is has warmed up to 15F.  Someone recently posted about building a partition behind the front seats and using ducting to get heat from the rear heater to the front.  I half considered this but thought that the kids might complain if I took their heat away.:>)

Mark in AK

----- Original Message -----
From: Andy Highland <andy@420.AM>
Date: Tuesday, November 28, 2006 11:55 pm
Subject: Front heater: low heat at highway speed
To: vanagon@GERRY.VANAGON.COM

> I've been using my van (1990 Westfalia) in sub 40 F temperatures for
> the first time. When I'm at freeway speeds, the heater is blowing
> cold air. When I close the floor vents, (3rd lever pushed to the
> right) the air gets a little warmer, but not by much. Basically, the
> heat coming out is totally inadequate, but only when going fast in
> cold weather. In more moderate temps, or when I'm on city streets it
> seems OK. So is my front heater broken, or is this how other people's
> vans work? I find it hard to believe that people up north could live
> with such a pathetic heater.
>
> Thanks,
> andy
>