1984 under dash vacuum line?
Thread Starter
Racer
Joined: Nov 2013
Posts: 338
Likes: 8
From: South NewJersey
1984 under dash vacuum line?
I found a skinny ,black ,hard ,plastic "line" on passenger side under dash, Its not hooked up to anything .upper dash is mostly still apart (interior restore) So I dont want to start engine to see if it draws vacuum .Can anyone tell me what it is ? Thanks
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
You have a vacuum supply line that comes in from the firewall. This goes into the HVAC unit. It goes too two areas on the unit, it has a T connector that splices it off to the vacuum harness for the vent door controls, and another one to the heater control valve controls. When you turn the heat on, the heater control valve linkage is fully extended. When you turn the setting to cold, the linkage becomes retracted. Vacuum goes to the heater control valve when on the cold temperature setting. I just went through this today with my 85.
Hope I can get it all back together 
Intermediate
Joined: Jan 2015
Posts: 35
Likes: 0
2nd Gear
Joined: Jul 2021
Posts: 2
Likes: 0
96 corvette not blowing air from front vent fix!!!!
Hey guys! I have been fighting this problem for a couple years now! My A/C would blow from top and bottom vents but not from mids. I took apart the passenger side dash and there’s a black vacuum wire that has a yellow/orange nipple connector. THIS WAS THE PROBLEM. The vacuum line was rubbed thru!! I cut a piece off re used the old connector and some glue, plugged it in and VOILA! Air from front vents!
