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Common fault on all 700/900 series with aircon is the failure of the 2 way vacuum bellow which controls one of the air circulation shutters, part number 9463042 for LHD, 9463044 for RHD. This cause a vacuum leak on the climate system, and the most common symptom of failure is that air stops coming out of dash vents under acceleration but resumes when you release the accelerator pedal. In severe cases the air circulation shutters may stop functioning altogether, with the system permanently stuck on floor/demist position. Volvo no longer produce/stock this vacuum bellow. I’ve known for a while that AC Delco vacuum below 15-71438 can be used as a substitute, however they are still sufficiently different to the point that it’s not going to be a direct fit. The orientation of the metal actuator rod & position of the hole on the rod is different, also the 2 vacuum ports will be in a different position so I wonder if the vacuum hoses are long enough to reach it. Then I noticed that the failure (vacuum leak) is always caused by a tear on the rubber seal around the actuator rod, so what if I just swap the rubber seal over... and it worked!!! I have just repaired my genuine Volvo 9463044 vacuum bellow using the rubber seal from AC Delco 15-71438 vacuum below.