I have a 2010 wrangler 3.8 that the radiator fan only comes on when the A/C is on. Tested the fan it was fine and replaced the relay. I also get two codes, P0128 thermostat rationality and P0693 cooling fan control circuit low.
Can anyone help?

 

Listen, I can't help with this issue, but I'll tag @ronjenx who might be able to help with this electrical issue if you'll kindly stop posting this same thread in different sub-forums. You just posted it for a 3rd time in the Write-Up section.

 

Sorry I figured more people would see it, besides I wasn't sure where to post it best with so many categories.

 

I just changed my ECT (engine coolant temp) sensor on my 2010 as a preventive maintenance against possible failure sending a signal to turn the fan on. The original was black plastic, the new revised version is brass and more robust. BTW, I did this after reading a post by MoTech explaining their experiences.

 

if the fan is coming on when the AC is activated, that means you are getting the high-speed side of the circuit. Besides the relay (behind the driver headlamp) there is a voltage divider (down by the blower motor) that can fail. If this fails, the LOW speed will not work. Kinda sounds like this may be your case.

 

You are talking about the high low resistor on a 2010 3.8, it's located on the fan shroud and I changed that second. I have changed the relay already now I'm going to change the coolant sensor as soon as it gets in.