Hi. The heater blower on our 88 560sl is not working. The pneumatics are activating but nothing from the motor. I've replaced the fuse and have power across the fuse. Somewhere I remember reading that the HVAC controls are temperamental and expensive to replace. How can I determine if it's the control or the blower motor malfunctioning. I've tried the archives at the mbz.org site but the sl listings are not available. Any help is greatly appreciated.