Hvac vacum problem

[zjuni]

Hello Fellows
Owner of 300 66 and founded some errors in hvac system. only "clap sound is heard when heat is pressed in heater control unit when vehicle idling. Cutted off the main supple hose from intake manifold to vacuum heater control unit. Inserted vacum pump to hose and applied 10iches of vacum to system.
Vacum drops rapidly and will no stay at all. My question is, is there any weak parts where to find malfunction first. Maybe actuators or heater main unit? Hoses still 50 years old, should be replaced first. If system overhaul needed where to start upper or lower? Dash pad removal needed? any suggestions ? Have apologie to my bad english but had few bear after sauna when writing this out...Thanks for awesome forum and greetings from finland

 

[Big_John]

Grab a service manual here and that will get you started.

MyMopar - Mopar Forums & Information - Service Manuals

 

[zjuni]

Hello
First stage of problem solved. Hvac heater door actuator has limited travel. Other side seems to keep vacuum but other side is totally out of resist when applying vacuum via pump. Is it possible to repair actuators or is it best way to buy new or good used one.
Thanks