What is the device in the highlighted area of the photo below? The engine is a B21F from a '79 242 (my parts car for the '80). The device is directly underneath the intake manifold, which is seen at the top of the frame, and is in-line with the hose that runs between the aux air valve and the idle control.
I ask because my '80 DL does not have this device. Just the hose connecting aux air valve to the idle control. And the vacuum connection on the '80 idle control is plugged with a screw. Also on the '80 there is another plug on top of the intake manifold where the '79 has a vacuum fitting that I'm guessing was connected to the mystery device. The connection on the device is hard to see. It's pointing stright at the camera lens.
I'm just wondering if Volvo changed something between '79 and '80 or if someone has modified the '80 not to use this item? Do I need this item for the '80?
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1980 240 DL

that is an idle increse valve for ac operation. it should have a small vacuum hose connected to an electrical solenoid on your firewall. it allows more air to bypass the throttle plate when you turn on your air conditioning.

Thank you. I figured it had to be some sort of idle control device. I have been looking in the manuals and visiting Volvo parts websites trying unsuccessfully to identify this thing. But I never would have looked under ac or climate control.
The '80 does not have ac so I don't need this device on it and that's what I needed to know.
Thanks again.
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1980 240 DL