Wow it worked. BTW the Multiplex control unit is what I am looking for.

 

The Multiplex Control Unit is plugged into the rear side of the under-dash fuse/relay box:

 

Thank You. Any other tips on why I wouldn't work? I have the factory instructions and according to them everything is plugged in.

 

More information would help.

Does nothing happen when the A/C button is pushed?

Does the A/C light turn ON when pushed?

When the A/C button is pushed, does the condenser fan or radiator fan run and/or does the compressor clutch engage?

Is the system filled with refrigerant to spec?

Are any fuses blown?

Have you tried to retrieve a trouble code (see below)?

 

I will try the Diag. But here is what I know now. The A/C light comes on and I followed system checking for ground all the way through. Except to the multiplex unit. I am missing the signal from the ECU to ground the system. But I have everything outside working normally as far as connections. I need the ECU to ground the compressor relay under the hood.

 

Are you saying that you cannot locate the YEL wire between the MCU and ECU (see diagram below)?

By the way, if you ground the YEL wire to the under-dash framework, does the A/C kick ON?

 

Yes and the blue/white wire at the fuse box. But also couldn't find the wires inside.

 

This may help (see connector terminals E10 and F9):

 

Thank You very much!!!! I will report back with my findings.