99 GC - A/C no longer works, then blower stopped

My 99 GC, 140,000 miles, 6 cyl. Was diagnosed with a dye. Leak is from the evaporator according to mechanic. Dye is seen on firewall passenger side. 1 week later the blower stopped blowing. Had resistor and harness replaced in '03 and again in '04. Had major melting at terminal end. Today; jumped blower motor - it's ok. No bad connections at resistor/motor as far as I can see w/out removing anything. When switch is turned on, light for A/C turns on and I turned it off. Hear a faint sound from switch when going from off to on. How do I remove / replace this switch? (Behind center dash) if this is the problem? Checked fuse in engine compartment (40 AMP) it's ok. No others found. Read about a switch in engine compartment on older models, is there one on 99? I feel I've eliminated the basics and am worried it is a melted harness again. Trying to save big money for the 3rd time. Will most likely have the evaporator job done (got quote of $600 cheapest) so I'd like to do anything else necessary myself.