AC part, what is this?

[Katfish]

While working under dash, noticed this small part had broken off at 1 end.
I'm guessing it's some sort of vacuum check valve?
It's small maybe 1" long with tiny 1/8" fittings.
It's connected to the vacuum fitting on the back of the AC control switch.

What is it, what does it do, where to get another?

[Rich G.]

That's a check valve to to keep vacuum in the system for the HVAC doors .

[Mrbill426]

Last time I looked you could get those at NAPA. 

https://www.napaonline.com/en/p/NOE7301347?impressionRank=1

While working under dash, noticed this small part had broken off at 1 end.
I'm guessing it's some sort of vacuum check valve?
It's small maybe 1" long with tiny 1/8" fittings.
It's connected to the vacuum fitting on the back of the AC control switch.

What is it, what does it do, where to get another?