installing air horn

I need to pull 15 amps to run an air compressor for an airhorn on a 1987 chevy truck. I put lights on my own truck but i do not know how to pull from the ignition wire or use an accessory fuse in the fuse box. i do not know how to ask specificaly about what im trying to do so the easiest/safest way to power a 15 amp aircompressor is what i need to know. thanks

An inline fuse assembly rated at 20 amps. Just attach the power wire to the battery then to fuse, then to air compressor. If you want to make it to where it turns on when you start the car (I dont know which wire is the ignition wire), but if you have an aftermarket head unit, you can use the power on wire from it and attach it to a relay. 

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Kenwood all the Way!

hook it up to your reg horn.

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Big Dave

I ran a 14 gauge wire from the bottom of my fuse box, connected to a constant hot, to one side of the pressure switch, then from the other side of the pressure switch, to the small post on a regular Ford starter solenoid. Ran a 10 gauge wire from the (+) battery terminal, to one side of the solenoid, and another 10 gauge from the other side of the solenoid to the compressor. This way the heavy amperage is handled by the solenoid, and not the wire to my fuse box, or more importantly, the pressure switch, that will burn up if it has more than 5 amps passing through it. I have a 2 gallon tank in front of the Rt rear wheel well, mounted to the frame. You have to be sure to put a drain plug or petc**k on the bottom. I bought the pressure switch that turns the compressor on at 95 lbs, and off at 140 lbs. That allows me to blow the horn, a few times before the compressor comes on. I was going to put an LED on the dash, to tell me when the compressor is running, but it wasn't needed, as I can hear it when it comes on and shuts off. Email me if you'd like more info, or maybe some pics..

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Sony Mp3 HU, Dig/Aud 300Wts
(1) 12"sony sub.. Aint much, but it looks good, and thumps like a rabbit on Viagra!

What type of horn system? Is this a compressor that fills a tank to a certain pressure and maintains that, or a compressor that runs the horn through a direct hookup?

Adrianspeeder

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'02 F250 PSD, '97 F-150, '71 F-100, '66 F-250, '93, '92, '88, '84 Broncos

Penn State electrical engineerin' major