Originally Posted by JGiardino89
Why would an electric fan come on when an engine is cold ? that doesn't make any sense. There is no heat to be dissipated.
I flushed everything very well, I am sure that I got most, if not all of the old stuff out.
Would a bad temp sensor cause the fan not to come on ? "Check gauges" came on, temp was pegged, but I looked under the hood and it was not over heating. But the fan was on.
Yes, a bad temperature sensor could prevent the fan to come on. This sensor sends its information to the PCM and the PCM sends the signal to the instrument cluster and a fan on signal to the fan relay.
On other jeeps which also have the mechanical fan on the waterpump, there is a constant base cooling coming from the mechanical fan. Jeepme said that on his jeep the electrical fan comes on as soon as he starts the engine. I don't know this setup with only electrical fan, but can be that the elec fan takes over the base cooling function when there is no mechanical fan.
You also have 12V on the fan connector, but did you check if the ground is ok as well?
But rereading your message you say that you had check gauges on, temp indicator pegged and fan on? So the fan is working, eventhough there was no evidence of overheating. Then i would just change the temperature sensor.