From the Audiovox Installation Manual --
A noise suppressor 'in series' with the blue wire keeps excessive electrical noise from "fooling" the cruise into disengaging. For this reason make sure all cruise control wiring is at least 1 ft. away from all electromagnetic sources such as: ignition wires, alternator, regulator, and all high current carrying conductors.
CAUTION : DO NOT MOUNT OR ROUTE WIRING HARNESSES OR KIT COMPONENTS ON OR NEAR ANY HOT, SHARP, OR MOVING SURFACES WITHIN THE VEHICLE.
You must also be sure that the cable is routed away from any hot, sharp, or moving components within the engine compartment.
Do Not mount servo on the engine !
This vacuum source must maintain at least a minimum of 6 inches of mercury vacuum. If the vacuum is lower than 6 inches while the pedal is depressed, then a vacuum canister must be used.