After 6 weeks of working on my climate control which was totally dead, I decided to change the switch. When I got way back in there under the dash, I found an empty plug tucked up in the wires. It was exactly the same as the plug already plugged in to the control switch.I swapped the two plugs and My heater fans started working properly on all speeds. Still no A/C but I don't know if that's related. Does anyone know why the two plugs ? and are they both supposed to plug in somewhere?

 

Have you got a wiring diagram?
From memory when I did mine I do not remember an extra switch but that was a few beers ago.
Some of the vacuum tubes had come off so the vacuum motors would not work and move the air from windscreen to feet and front grill.
Are those working?