I’ve attached a picture of these valves from my 1997 car with ECC. Mine have never been disturbed and appear to be the same orientation as yours.
Problems with the vents are often down to the vacuum servos. Your symptoms seem a little different from the normal face vents stop blowing air when the car is under acceleration There are details on replacing these units in the FAQ.
https://www.volvoclub.org.uk/faq/OEM...tVacuumMtr.pdf
It is possible to bypass the one that most often leaks by disabling the recirculation feature which might be worth exploring if only as a non-destructive test.