The button for the rear A/C does not click when depressed like the button for the front, you have to keep it pressed manually for the rear blower to work, and the indicator bulb does not turn on ,( for both buttons of the rear A/C , front and roof ).
You can hear a ticking sound from the rear A/C unit when button is pressed,
relay ? , any experience with that, help needed , thanks.

Discovery 97, 3.9, in good shape, except for that.

 

Quick way to check switch is to do a swap with the working one.
They pop right out

 

There are three buttons for the a/c , one main (primary front a/c switch), two secondary for rear( main rear and passenger rear a/c switches) these wont start unless the main is on , I don't believe you can interchange as they are different in wiring diagrams. The two for rear are the ones that can be swaped but unfortunately both do not click nor illuminate, and each will need to be held down for the rear blower to go.
I have the wiring diagrams for air conditioning and blower controls, from Haynes , but same problem solved by somebody will get me away from this difficult diagram .
Thanks dusty 1 .

 

i see... then my vote is def. not for 2 faulty buttons.