The recirculating door on my 300SD is not closing in A/C mode, but it does close in the "OFF" position. I checked the voltage at pin 7, which should have 12VDC in A/C mode, but there is no voltage. In the "OFF" position, pin 7 has 12VDC. I can jump pin 7 to 12 VDC and the door closes. Is there another component in the climate control system that could cause this problem? I have tried another climate control module, with the same symptom.