HVAC Vacuum Leak

[Chuck Henderson]

My 1970 Dart has the vacuum-controlled heating and air conditioning system. This is the system with about five vacuum-operated damper actuators and about 10’ of vacuum lines. I decided to replace the section of vacuum line from the intake manifold to the control head because it had been cut & spliced by the P.O. Okay, that job done, I thought I’d check the system by pulling a little vacuum on it. We’ll, it won’t hold any vacuum at all so I’m thinking my HVAC system is essentially a big vacuum leak robbing my motor of power.

I want to keep the system but I’m wondering if there’s anyone who’s dealt with a similar situation? Would I be better-off pulling the HVAC box out from under the dash and replacing all the vacuum lines and vacuum-actuators, or looking at an aftermarket modification? I already know my compressor needs replacing, and that means a handful of other A/C parts get replaced-receiver/Drier, Freon, seals, etc…

Do any companies sell aftermarket kits for A-Body cars with factory A/C?


Thanks folks!

 

[Demonic]

It's not going to hold a vacuum like a HVAC system. Some years have bleed resrtictors, and anything that old may have a bad diaphragm somewhere. IIRC, the spec is around 6-8" and there's a procedure with a rubber tip probe in the FSM.