Re: Manual Rad. Fan Switch wiring diagram
It would be ideal to wire a switch in such a way that the fan can be turned on by you, but still be wired to a temperature switch so it will turn on automatically. Most radiator fan temperature switches ground when the rated temperature is reached. This completes the signal circuit of a relay, which then handles the heavier current needed by the fan. This sounds like the gray wire for the spal fan. The safest way to wire this is to have the gray wire "y", one branch of the y goes to the temp sensor, and the other branch goes to a toggle switch that is wired to ground. When the toggle closes it provides ground and will signal the relay to turn the fan on. However, this also leaves the temperature switch capable of turning the fan on if the toggle is left open - the temp switch now provides the ground. This is safest because even if you leave the switch "on", it will not harm the temp switch -you just have two sources of ground hooked to the relay's signal circuit. In this way, you can have the manual switch as an override but retain the automatic function of the fan switch.