I used to have a problem on my car, which I'm guessing is not unusual,
of dashboard vents not opening because of poor vacuum connections.
There are three fittings on the firewall directly behind the air
receiver/dryer, and a long plastic vacuum line that connects to some
unknown valve (?) on the other side. The little rubber connectors on
my car dried out and cracked from time, so I replaced them with pieces
of generic rubber tubing that I got at Autozone, which took care of
the problem that I was having. Now, I was hoping to replace these with
time with the proper ones (I think the tubing from autozone said
"gas line"...) but I can't find the parts numbers, and in fact,
no mention of the connections in any of the manuals that
I checked.
Anybody knows where to look for these? (And what do they actually do?)
And in fact, is it worth bothering to change them with "genuine
Volvo" tubing?
PS. The car is a 1998 V90, 150,778 miles.
--
'98 965

I have a v90, and have a vacuum leak also. There are three vacuum connections
on the fire wall. One feeds out to the heater valve, and one (drivers side) seems to control the vents for top and bottom as I can pull a vacuum on it
and the air will come out the top. Does anyone know what the other one on the
passenger side goes to? It leaks bad enough I can't pull a vacuum on it.
I have taken the under dash cover off and these are behind the glove box or
the heater box so with out taking everything apart I can't follow the hoses.

The unknown valve on the left side is the heater control valve.Any tubing that does not leak and isn't kinked should be OK in place of the factory elbows,which are a little pricey.

The main reason I have found for vent selection problems is a defective vacuum distributor.It is located at the left end of the glove box on the heater case.It costs $200 dollars at the dealer but can easily be repaired.

Remove the under-dash panel on the passenger side,the two mounting screws,one wire plug and one vacuum hose manifold.Inspect the solder joints at the wiring connection with a magnifier and a strong light source.You will find one or two cracked solder joints at one end of the connector.Carefully re-flow the affected solder joints and your vent function will return.

Bill