Where, exactly, is my orifice tube?

[Phantom240]

I'm gonna try to tackle A/C this weekend, and I have no idea where my orifice tube is, physically, in the front A/C unit of my 99 Denali. I'm trying to figure out why 1) The A/C compressor won't kick on, but will kick on when I jump the switch on the accumulator (likely a bad switch), 2) When I jump the switch, I get ice cold air from the rear vents, but not the fronts (Going to check blend door), and 3) Check mode actuator function, as I can't get it to blow from the front vents, no matter which mode the selector switch is on.

 

[SunlitComet]

kinda of a loaded title question you think? first if the switch is not working properly replace it. with ignition on and fan on any speed except of, slowly turn your mode knob while observing the mode servo motor near the top and right of the gas pedal linkage for proper movement. your orifice tube that works the front is number 21in the picture below.
http://www.genmotorinfo.com/Picture...+AUX+A/C+C69)+-+CK1,2(06)+&pid=970516TC09-124

 

[Phantom240]

I believe the switch is bad because when I jump the connector, the compressor clutch engages. Otherwise, the clutch doesn't engage regardless of how much refrigerant is in the system or what setting the system is on.

So, looking at that picture, my orifice tube should be on the front side of the firewall?

 

[SunlitComet]

no sure in with out a pic in front of me but follow the line from the condenser where it splits. and look a bit farther. the orifice area will have a section of tubing slightly larger in diameter and have fittings on it. #21

 

[Phantom240]

Sweet. Looks like $12 plus new R134a might get me some cold ass A/C, if the rear A/C was any indicator of the capabilities of the truck. lol