Posted by John B [68.69.26.160] on Thursday, April 09, 2015 at 20:55:00 :
In Reply to: Relay question posted by Tim Holloway [69.54.28.229] on Wednesday, April 08, 2015 at 21:56:27 :
Tim: You didn't mention if they gave you a wiring diagram. I assume the vehicle is wired for 24 volts. And as the other guys have mentioned, do not put 24 volts on to the 12 volt coil wires or the smoke will come out of it in short order.
My thoughts regarding the relay is that it is to be wired into the circuit so that the compressor cannot get power with the ignition switch in the off position. I also think there should be a single pole toggle switch in series between the ignition switch and the relay coil wire. Leave that switch in the off position until the vehicle motor is running or until you want air. Otherwise if the pressure switch was in the closed position (calling for air) the compressor motor would be running while you are trying to start the vehicle motor.
I would install a fuse of adequate ampacity (from the wiring panelboard or inline) in the power conductor that feeds to the line terminal post of the relay. One conductor from the compressor motor of course connects to the corresponding load terminal of the relay. These terminals may not be identified, but that does not really matter anyhow. There will likely be an extra set of contacts on the relay, but just use any two termials that make and break together.
Connect the other wire of the coil and of the compressor motor to a good clean solid ground. Ensure that the relay contacts are heavy enough to carry the motor amperage.
I hope I haven,t missed anything here, and that this info may be of some assistance. JJB.
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