I usually always drive with the heater controls in the DEFROST position, with the fan off. I've noticed as of late, that it will stop directing air there occasionally.

 

If I have the heat on, in the Heat position, and then click it to the defrost position, it doesn't always seem to take. By playing around with it, i've found if the engine is in vaccuum it has a greater chance to switch.

 

What could be the problem here? I'm pretty sure it has to do with the vaccuum actuated part of the system. It could very well be at the engine compartment end of things... I have messed around with the vac. lines quite a bit.

 

Any insight would be appreciated!

Hey Tex (I assume I can call you Tex )

 

 

My wagon will do that sometimes on a hard pull (low vac), I think that the VENT setting is the default for the system without vacuum applied. It could be a bad/leaking check valve in the line that feeds the vacuum storage tank. Or there could be a small leak in the heater control vac system so that its depleting the vac tank during low vac/boost conditions.

 

 

Just my first thoughts

 

Gary

Ok, That all makes sense. Now... I have a feeling its because of how my vac. system is set up (on the engine side). I guess I'll try hooking them up a different way.

 

Sometimes modifying is a pain in the arse! I just want my windows to stay clear.