Volvo Repair: Volvo 760 AC Control System Blower Vacuum Hoses, air conditioner blower, vacuum operation

Question
The car:

1989 Volvo 760 Turbo

Issue:

The air conditioner blower either turns off the face vents or slows the blower down when I accelerate the car. I think it is a vacuum control problem and so checked the hoses in the engine compartment and replaced the ones that were cracked. The check valves near the intake manifold seem to only let air through one way when I blow on them.

However, the problem remains. Some of the other vacuum hoses to the emissions system and other systems are cracked and need to be replaced. Would these other hoses being cracked affect the vacuum operation of the ac system?

Any advice would be greatly appreciated. My wife drives the car, is 6 months pregnant and the temp here is well over 100F! Thank you.

Answer
Sam, Its one of the vacuum diaphragms.  Most likely its the recirc diaphragm.  Thats the easiest of the ones to replace but I highly recommend your Volvo shop perform the repair.  I dont even like to do them.  The only vacuum lines that would cause this are the ones going into the car.   Roger