Climate control harness connection repair

When the climate control panel is out of the dash everything is adjustable; temperature, fan speed, etc. When the control is set into the dash all control fictions are not adjustable. It is a harness connection issue with that grey plug circled by one of the earlier posters. What is the issue with that connection to have constant control of the panel? I do not have voltage testing equipment, besides the adjustable function is it not at the panel once it is in the dash. Someone give accurate answer please.