Hello there, need some info. Just bought this truck, and the HVAC doors donot work, stuck on defrost. Main vacuum port to hvac plugged at "T" coming off intake. Where does tha HVAC line enter thru the firewall into cab, cant seem to find a loose line entering. Found all the info for the front axle lock up, to return to factory, right now it is manuel. So I know the vacuum for HVAC "T"s off the same source, just mine is plugged and line is missing.

thank you for any help

 

What year and model blazer you have? And did you swap the manual transmission in there? Also is it 4x4?