AC vacuum hose routing

[mikemileski]

I need some more detailed information than what's given on the attached diagram. First of all, I have a '72 GMC with factory air and a 350 engine. The only "vacuum source" that I can see on my truck is a solenoid looking thing mounted on the intake manifold on the passenger side of the carb. Only it has three vacuum nipples on it. One is on the backside along with an electrical connector, and the other two are on the front. If this is the "vacuum source", which one of the three nipples do I use to go to the vacuum reservoir and to which connection on the vacuum reservoir does it go to, the large nipple or the small? Also, exactly where is the Control Head Vacuum Switch located under the dash? If there's any Tucson guys that have factory air and would be willing to let me see their setup, that would be great. Thanks in advance for any help.

Mike Mileski
Tucson, AZ

(PS - I originally posted this in the 1947-1959 forum by mistake. My apologies)

[cdowns]

theres excellent diagrams and illustrations of the vaccume hose system in the factory assembly manuals sold by most vendors

[leddzepp]

You need a vacuum source...any of the three you are describing will do. Just make sure the other two nipples are either plugged, or are operating other accessories. The vacuum source connects to the large nipple on the reservoir. The vacuum contol switch is located on the backside of your A/C controls, as pictured below (top view of A/C controller removed). You need to remove the A/C controller (two screws underneath) to access it. Hope this helps.

[71 super]

The source you have referenced is the TCS solnoid, you should have a nipple/fitting located between the distibutor and carb. It should have two nipples- one connected to the auto modulator valve (causes the trans to shift) a bare nipple for the connection from the a/c reservoir located on the evap case on fire wall (black and round/disk shaped with two fittings on the back), the third goes to the power brake booster if equipped. You will have a line from #1 port located on heater head unit to reservoir, and #2 will tee if early head unit , one side coming off of tee will hook to fresh air vent on passenger kick panel, the other will enter engine compartment and tee again one side to actuator on firewall for fresh air on kick panel and other the heater cut off valve in passenger inner fender. If you have a later three prong valve on head unit you will delete one tee from previous assembly and continue as above.

[mikemileski]

Thanks for all the great info guys.

Mike Mileski
Tucson, AZ