Volvo: Loss of blower air volume, auto repair shop, volvo 960

Question
We are a small auto repair shop in Michigan.  WE have a 93 Volvo 960 wagon.  Our customer looses air volume on acceleration from his blower motor.  We have replaced both check  valves and checked the vacuum resivoir for leaks, there are none.  Have you run into anything on this problem.  If so, your input would be appreciated.

Kathy,
Master's Auto Maintenance

Answer
Hello Kathy! There are 3 vacuum servos under the driver's side dash attached to the heater box. There is 1 with 2 ports on it. That controls the floor/defrost function. The servo is probably bad. It is a very common problem. Very difficult to replace if you are unfamiliar with it. Look me up at www.jlcarclinic.com so we can talk about it. It is very difficult to explain the repair procedure via email.

Jimmy