The 3rd gen HVAC has 2 vacuum lines connected to the hot/cold selector. When the selector is all the way on the 'Cold Position' the vacuum is opened between these 2 lines (pink & gray) to divert coolant. After about 1/3 of the levers travel towards the 'Hot Position' the line is closed.

Has anyone been able to make this functional with their 4th gen controls??

The only info I've seen on it is that everyone just makes the line closed all the time. It's the only part of my HVAC I have left before I have 100% functional controls (I even got the vacuum servo for mixed mode hehe).

 

that was just covered on another thread, let me try and find the link for ya....

 

Thanks. I'd really appreciate it.

 

https://www.thirdgen.org/techbb2/sho...hreadid=289600

 

That thread just deals with the vent selection vacuum. I'm talking only about the 2 vacuum lines that control the Heater Control Valve.

 

oh, ok, im sorry that didnt help...

 

Back from the dead. Any progress? These HVAC vacuum lines are driving me nuts ...

 

yeah, updates anyone????