An air horn is an auxiliary horn that uses an air compressor to produce a tone that is considerably louder than a factory car horn. Usually, air horns come with a compressor, relay, tubing and 2 horns that each produce a different tone. Before installing an air horn system in a vehicle, consult your local laws to make sure that doing so isn't illegal where you live. Many cities and states have noise regulations that prohibit the use of after-market horns.
Open the hood of the vehicle and find a good place to mount the horns. The horns should be mounted facing at a downward angle to prevent water from collecting inside. They should also be located toward the front of the vehicle.
Mount the horns to the vehicle using self-tapping screws and the mounting hardware provided. Avoid mounting the horns in places where they will be subjected to excessive heat and moisture or near any moving parts.
Mount the compressor to a fender or firewall with the appropriate hardware. Run the provided tubing from the compressor to the horns. Avoid running the tubing near hot or moving components. When possible, run the tubing with factory wiring harnesses and secure it with nylon wire ties.
Use a multimeter to locate and test the horn wire. This wire will read 0 volts at rest and 12 volts when the horn is pressed. This wire can easily be found at the horn itself or at the horn relay. Connect the horn wire to the relay along with power, ground and the 12-volt output to the compressor, according to the instructions included with the air horn kit. If the instructions are not available, wire Pin 87 of the relay to 12 volts, Pin 85 to the horn wire, Pin 86 to ground and Pin 30 to the positive lead on the compressor.
Mount the compressor to the fender, firewall or somewhere free of water and excessive amounts of heat. Connect the negative terminal on the compressor to ground. Test the air horns by pressing the horn button. If installed correctly, the air horns and factory horns will sound.
