I'm a long time lurker, but fist time sender.

I have a 90 V'gon GL, and I only get hot air from the dash vents. From the archives I know that there is a valve in the hose that is controlled by the temp slider on the dash that can go bad. Is there anything else that can cause this, or should I just go get a replacement valve? If it helps any, I got the heads replaced about 4k miles ago