HVAC Vacuum Lines

[turbodaytona87]

I removed the HVAC box from my Daytona to replace the heater and evaporator cores The vacuum lines exiting the box by the heater core have been broken/disconnected for a while, but while the box is out, I would like to repair those. Where can I get line that small?

[turbodaytona87]

From some digging around/measuring, I think the HVAC control lines are 3mm OD or 1/8" OD I'll double check the 1/8" fit today. I really just need a way to connect the HVAC box to a vacuum source since my connections broke off at the firewall.

Maybe someone can answer these: Why are there two vacuum sources into the box? Also, which vacuum lines go to which actuators?

[going4speed]

the two vacuum lines are one manifold vacuum and one to the heater control valve under the hood. The manifold vacuum goes to the ac control. Went heat is called for from the panel then a vacuum is provided the other line to actuate the heater valve thus allowing for water flow throught the heater core.

[turbodaytona87]

the two vacuum lines are one manifold vacuum and one to the heater control valve under the hood. The manifold vacuum goes to the ac control. Went heat is called for from the panel then a vacuum is provided the other line to actuate the heater valve thus allowing for water flow throught the heater core.

Yeah I found that later today. In stock configuration it does that, I don't have a bypass valve though. It was broken in the middle of February, and I didn't want to mess with it, so the heater core is fed directly.

I still need to know which lines go to which actuators though.

[turbodaytona87]

Ok figured it out, I was missing an actuator.

Here are the connections:

Recirc Door Actuator (right/passenger side of the box, by the blower motor): Light Green goes to the top nipple, Dark Green goes to the bottom
Front Panel/Feet Actuator (left/driver side of the box, upper actuator, two nipples): Red goes to the top nipple, Brown to the bottom nipple
Defrost Actuator (left/driver side of the box, lower actuator, one nipple): Yellow
Vacuum Source (under heater core lines, black, left/driver side): Black with one way valve
Coolant Control Valve (under heater core lines, gray, to the right of the black line): Gray

Since my vacuum source and heater control valve lines broke I needed a way to fix them. I bought two 5/16 brass barbs



some 5/16 vacuum line (actually probably slightly too big to fit around the stock lines snugly), and some two part epoxy.

I epoxied the hose barbs in the factory location, replacing the stock white piece with the broken black and gray lines.



Then I inserted the factory line into the 5/16 line and epoxied them in place (because 5/16 is slightly larger, you can see the gray line drying on the right of the image above.) making sure to keep the vacuum line openings clear. Once the epoxy dried I could connect the short piece of 5/16 line to the interior side of the hose barbs. The engine side of the black line will go back to the brake booster branch, and the gray barb will be capped (no coolant valve currently).