4230 Relay Questions

[JD5210]

I am helping a friend fix the relay for the air conditioner on his JD 4230 diesel cab tractor. He had a person replace all the wiring some time back and said it work for awhile after he got it back. 4 wires, ground, wire to the blower/wipers, power wire from a circuit breaker (CB) and another power wire that is only hot when the key is on.

My question, the power wire from the CB is always hot even when the key is removed. This to me is wrong, since the CB wire is on the coil causing the relay to be always on, even when the tractor is not running. To me this wrong, what do others think? He does not have the old relay, but to me this is what burnt it out.

What I am thinking of doing is switching the 2 hot wires. This way the relay will only come on when the key is on and the always hot wire will be connected to something only when the relay is actived, by the key being on. Good plan or not?

 

[atschirner]

You are correct Sir!

The relay coil should only be powered when the key is on. One exception to this rule is if the ground side of the relay is switched. In that case B+ to the coil is acceptable since the ground is being used to switch the relay coil. Not only will leaving the coil energized over heat it; the battery is also being drained when the alternator is not turning to recharge it. Any past dead battery issues gone unexplained?

Good luck, Alan

 

[Tx Jim]

I agree with Alan that the accessory relay should only be energized when key is on but the wire from the circuit breaker will be "hot" all the time as that's the purpose for the relay. The relay circuit normally utilizes larger wires than the ignition circuit to help with the electrical loads such as AC or lights.