Will the dashboard switch for existing oem horn work on a dual trumpet air horn? Will I need a relay or is the switch rated for the draw on the air horn?
A relay is a good choice. Do you have the specified current draw for the horn?
There might already be a relay for the existing horn. Did you check the wiring diagram?
Another good idea is to add a snubber diode to protect the relay contacts from the inductive kick when de-energizing the horn. Without the diode the relay suffers arcing at each usage.
Will the dashboard switch for existing oem horn work on a dual trumpet air horn? Will I need a relay or is the switch rated for the draw on the air horn?
Air horns (good ones) usually work a little different way than small electric or on-demand air horns.
Better, bigger air horns have compressor with air tank and to "make a sound" button on dash activates electric air valve and release air from tank. This kind of horns have practically no delay to make warning sound. On demand compressors need some time to create enough pressure and this may take 2-3 seconds. OEM switches are usually listed 7 - 10A
