Because I have the same problem on all three of my 940s (not as bad on the single non-turbo car, but it has half the mileage of the other two) I assume this is a problem that is characteristic of this model.

The FAQs on HVAC are extensive and I have skimmed them, but it appears there is only a small amount of information on my kind of problem and that surprises me.

The air conditioning is working adequately, but on acceleration the air vent close down completely and only reopen when coasting.

John Sargent posted an FAQ on this subject referring to check valves as shown in an accompanying picture, but I do not see a picture associated with the posting and it would be helpful.

In the past, I have been advised by the mechanic, I no longer have confidence in, but confirmed by others, I do, that the repair of the faulty vacuum check valve which is almost certainly the cause of the vent closing is big, big job involving dismantling most of the underside of the dash and then it is still a tough job to identify the specific problem.

I would like to know more about this.

As an alternative, is there a way to mechanically open and secure the vents for the Summer to get air conditioning?

This is important because if I can get the cool air to flow into my '95 Navy 940, I might be able to persuade my wife to keep driving it, instead of spending $20,000 to buy her a used XC 70. She drove one at the local dealer last week and now it a xc70 love affair.
Thanks, as always.

Bob Franklin