A/C Switch
 

2002 Madza Protege LX, A/C only comes on when the blower switch is in low "1" position. Blower works fine on 2,3,and 4 position but A/C light and compressor do not come on. Connections in back of switch and switch check out OK. How does the A/C sense the position of the blower switch and enable the compressor (yes, the A/C button is pushed in and is in the "on" position)?
Thanks for any help.