Electric Fan & temp sending unit control (1 Viewer)

[MBOffroading]

Ok, so I'm finishing up my switch panel and electrical "to-do's".

Currently, I have my electric fan (high setting) on a rocker switch, and would like to add a temperature controlled switch.

If I purchase just a sending unit, that kicks on the high speed fan around 205*, how do I wire it into the existing setup?

Current high speed setting wiring;
IGN HOT > Rocker Switch > Relay > High Speed on the fan.

Basically the high speed will only active while the ignition is on, and the rocker switch is turned on.

I "think" the correct setup for this would be something like this.

IGN HOT > Rocker Switch (override) > Relay > Sending Unit > High Speed. I'm thinking the sending unit splices into the IGN HOT (86) on the relay, so when the SU gets to 205* it will trigger the relay to kick on.

 

[Bret]

The simplist way is to wire the temp switch in parallel with your rocker switch. You can also put another rocker in series after the ignion switch if you want to manually turn it off.

 

[MBOffroading]

hmm... I'm sure I'll have to draw up a diagram on how to do it the right way, never really done wiring like I want to with this setup.

 

[fieldsken1]

why do you want a rocker switch for it??? just wire in the sending unit to a relay to turn fan on when it reaches temp and it will turn off at a set temp. if you need to jump it in a emergency just run a hot wire to the fan

 

[MBOffroading]

I want to be able to override it if I need to.

 

[Bret]

If you want to overide it it can be just unplugged from the relay or fan. The only danger in an overide switch is the chance of it getting accidently turned off and overheating. Another caution is not to wire power for the fan from the stock harness. Some fans can pull enough current to cause problems. Direct connect from the battery to the fuse to your relay to your fan. The relay control voltage can come crom the stock harness through your switch and temperature switch. If you have a switch to turn off your fan consider a warning light to ensure your aware its bypassed.

 

[MBOffroading]

Currently both the low speed and high speed are controlled by relays. Each is triggered by an IGN HOT on the relay, and power is pulled from the battery.

 

[My4x4FJ40]

will this work for you.

thanks
lee

 

[MBOffroading]

will this work for you.

thanks
lee

View attachment 578264

Seems a bit more complicated then it needs to be, but I don't know exactly.