You could call Volvo or windshield shops in your area for advice and direction. Verify with the BBB and perhaps these web opinion and review sites like Yelp?

https://www.brickboard.com/SHOPS/

http://www.volvomechanics.com/

http://www.cartalk.com/mechanics-files

You may ask them to remove the windshield and perform repair to the windshield pan pinch weld. They'll need to preserve the two drain whole either side of the bottom horizontal channel. These can get clogged, Yet more usually, the cause of windshield pinch weld is some not very good windshield technician using a razor, liek a box cutter razor, to cut the gasket of a windshield you want removed. The razor cuts the paint and the galvanization, cause the rust over time.

Windshield replacement technicians will use a hot electric knife to cut through the windshield gasket. The hot knife is a fixture that allows an even cut of the adhesive from inside or outside the windscreen. These are made of butyl rubber tape at the Volvo factory. All cars use urethane adhesive. Yet on some kind of windshield pan pinch repairs, use of urethane may not be the best. You have to be careful removing the windshield the next time.

In the older days, a windshield technician used cutting cable and shims to cut the (usually then) butyl rubber gasket. Stick the shims into the newly cut gasket to halt re-adhesion of the windshield you mean to remove.

Some attention may be required inside the affected A-pillar as rust can migrate to the interior of the a-pillar or other blind space or void where unibody sheet metal panels come together, like at the windshield pan pinch weld.

I performed this repair on probably rather small rust holes using the the POR-15 process. This is a cold way to repair, and you may use body filler.

I use butyl rubber. The only windshield I could get was Pilkington, made in China, with a crappy plastic frame to which the rubber flange would feebly attach to this plastic frame. I had to stop a few time as it detached at high way speeds so I could retrieve it.

If you can, get a Made in Europe Sekurit-Saint Gobain, or, if they still exist and made or inventory windshields for Volvo 240, Sunex, Scanex, Trempex, and a few others. In North America, you'll be hard pressed to find an optically good, strong windshield that is made in North America. Maybe the Made in China glass is better, now? Why I suggest buying a windshield from Europa. Though the price will be most dear.

The Made in China Pilkington on my 1992 240 GL is not made very well, is very thin, and optically poor. The glass and the laminate between the glass layers.

Hope that helps.

Questions?

Oatmeal Raisin MacDuffed.
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Jonathan Harshman Winters III: The Mightiest, Greatest, & Most Powerful Comedian, Presenter, Comedic Actor, Artist, & Author of North America in Perpetuity