Heater Box Air Leaks

[JB Popper]

Hi Everyone, I have a 1987 ChevyVan-based Class C Winnebago.  In fair shape for its age.  Last weekend,though, I had to drive home in 100 degree heat for about 130 miles.  I think the dash air is working okay, but I seemed to have a lot of air leaks through the heater plenum and could not really shut off the heat coming through the defroster vent.  I couldn't keep it very comfortable while driving at highway speeds, but in every small town at around 30 miles an hour, it felt good again.  Has anybody had to work through this and have any advice?

Thanks,

JB

[Rich Thomas]

It could be that the foam in the ducting joints have dry rotted away. Last time out in my 78 TravelCraft I hit the defroster and was inundated with bits and pieces of dried out foam used as gaskets on the tubing. It maybe that a chunk has broke off and won't let a vent door close all the way. about the only thing you can do is to follow the air duct and find the vent door and see if it is actually closing. LMC truck has a van section but I'm not sure if they sell the foam gaskets or not you can scope that out. hope this is of some help. sorry it's not more help