Does anyone have an extra vacuum valve 9463042 or know a good way to fix an old one. I am replacing heater core and would like to replace the valve if I can find one. Thanks

Yes, a perfect time to do this now that you've got the air distribution box opened up. I'm a bit jealous as I've got one or more failed bellows in both my 940s. You'll note you have two different ones -one has a double action and the most likely to fail. These have long been NLA in the Volvo parts chain, so don't even bother waiting for a reply from parts houses that still list them for possible order.

There's a crude bypass you can do by plugging one port and its hose, but it's less than satisfactory and that bypass didn't last long in the one 940 I did a few years ago.

If you search around hard enough, someone posted somewhere of finding a GM Delphi one that can be adapted, mostly it was just the mounting as I recall. I don't know if that part is still available.

.......Ah, found it here on Turbobricks!!
https://turbobricks.com/index.php?threads/part-for-2-port-ac-delco-or-a-c-t-s-ltd-vacuum-bellows.329764/

Failing that, I'd be very tempted to find a yard that might be willing to sawzall out a bunch of those for you to try.

Keep us posted here on your progress as that project is betting higher on my do-list, especially in winter.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Thanks a bunch. I ordered a new gm part #15-71438. The rod is a bit different, but it will work. I have new Volvo single pull that I bought 10 years ago for my 960 but never used. My son will be so happy to get his heat back and the ac working even when going up hill. Thanks for the help.