Ok so here a pic of the problem I think. The red line is where a vac. line from the intake goes in to the Canister Purge Solenoid the red line does have vac. the yellow line is a 3 way the connects the Canister Purge Solenoid to two other things none of those lines have vac. the blue line goes from the 3 way to the part i was saying that i dont have a clue what it is the blue line has no vac. the green line is the line that goes over and inside the car to work the heater controlls and it also ts to the vac. canister under the battery does not have any vac either all the lines are good. I hooked the line that goes to the vac canister and into the car(the green one it the pic) to the one from the inake (the red one in the pic) all the controlls worked great and the vac. canister had vac. to it down under the battery. if hooked up they way it is suppose to be the on line that has vac is the one going to the Canister Purge Solenoid does that mean its bad? no vac. is getting to the other lines that are hooked to it
The CANP solenoid only supplies downstream (canister purge) vacuum on a command from the PCM which trips the internal valve, thus porting vacuum and vapors to the intake manifold. This usually happens at an off-idle steady cruise situation.
As far as verifying the correct hose hookups you need either the underhood vacuum diagram, a GM Service Manual, or a good pic from someone with the same exact engine.
Ryan, just looking at it analytically, if the "yellow" line is dead, then the problem should be before that juncture inside the CANP. I also noticed the FPR is hooked after the "yellow" line so you could have a fuel pressure issue too. It seems to me the yellow line should have a vacuum at all times. Sorry, your engine looks different than mine - I have the 4.6L.
Yup - after looking again I saw that. So the main source of vacuum is from the "red" line to the CANP, then to the "yellow" line which conjoins to the blue line ending up at the PCV valve? It seems an odd place for the "green" line to take off from which you say is the main for the A/C modes. Do I have that right?
To clarify, if at idle there's no vacuum on the blue line, the problem should be at the CANP as you need a vacuum passed to the green line to run the AC mode. If there is a vacuum on the blue line at idle and nothing on the green line, then the problem is most likely the evap purge switch.
I hope I have the terminology correct...that would mean the rectangular device with rounded corners shown just above the FPR is culprit. BTW, did you pull the "Yellow" U shaped line off from that device to be sure it wasn't a blocked line? Highly unlikely, but just to be sure. Good Luck.