This portion of the 7-way vacuum connector tends to crumble after 15-20 years.
My recommendation is to cut off both sides of that connector (not at once, though) at the mid connector and splice with regular vacuum hose. I can’t remember what size the hose is, but you can always take a “cut-off” piece of the plastic hose to auto parts store.
A splice that is a bit longer than 1” (3 cm) works great. No need for glue or tape (unless you wanted to).
What I do after the splice job is complete, is take some colored Sharpies and add some color on the “black” hoses in case you need to take something apart again down the road. Most plastic tubing is colored, but some are all black.
There are three different 7-way vacuum connectors on your car. One at the A/C control head and the other two at a junction in the vicinity behind the ashtray. All three of those 7-way connectors can crumble on you just by looking at it wrong. The hoses are generally good, just the cheap material used for the connectors.
This is out of my ’86 FSM (Factory Service Manual) for heater only (not sure if your car is A/C or not). A/C hose diagram is in a PDF file at bottom of this post.
This is for A/C with SATC (Semi Auto Temp Control) – but I ran arrows to vacuum hoses to help you identify them
Purple arrow is the mid-way 7-way connector.
Gray arrow is black and gray hose that goes through firewall at spot shown) to manifold (vacuum source) and hot water valve.
Red arrow goes to defrost door vacuum motor
Purple arrow goes to A/C mode door motors (upper and lower)
Green arrow goes to recirculation door motor.
The A/C vacuum hose pinout is
1 Dark Green (Recirculation door) and Gray (hot water valve)
2 Red (mode door)
3 Black (vacuum source – intake manifold)
4 (sealed off)
5 Brown (mode door)
6 Yellow (defroster door)
7 Light Green (recirculation door)
The black hose under-hood can get brittle and break is not treated well - but it can also be patched up using a short piece of vacuum hose. If the black hose is broken, then there will not be any vacuum to operate the vacuum motors.
I hope this helps.
BudW