: heater control valve question

07-14-07, 07:05 PM
Hey all,
I have a 79 CDV. I'm reading 15 psi of vacuum from the heater control valve vacuum line, but I'm pretty sure it's not closing. Is it insufficient vacuum or the valve?

Also, how much are do the 79 blowers put out. It seems kind of weak to me. Is that just how they are, or has mine slowed down?


The Ape Man
07-14-07, 08:50 PM
My '77 had weak airflow. Turns out the evaporator was loaded with decomposed leaves. The stuff was several inches thick. If the cowl isn't kept free of leaves the stuff will get sucked into the system. Pulled it all apart, cleaned it out and it worked like a Cadillac should. Dunno about the stuck valve. Try it with straight manifold vacuum and see if it starts to work.

07-18-07, 11:51 PM
thanks ape man,
I replaced the heater valve, and it seems to be working.