The pressure has to be Between 280 and 330 PSI for the fan to come on.How cold is outside (ambient temperature).

Ok thank you all for your help. I have power to the fan plug so all is good to that point. I jumped fan to battery again and it does nothing now that it is hot. I jumped it yesterday before bringing jeep up to temp and it worked so ill let it cool down and try it again for my amusements only. Sounds like I need a new fan. Thanks again for your help!

Yep let it cool down jump it out and it runs. I need a new fan.

Newer model xj coolng fan does not come on unless high head pressure or high engine temps call for it..unlike older xjs where it operates when ever ac compressors engaged.

That's what i thought I read somewhere.

A/C does control "efan on", as well a coolant temp determines efan on. When a/c line pressure reaches X the efan is turned on in '00-'01 XJ's.
A/C "efan on" occurs when the compressor engages on '99 down XJ's. I have read that '00-'01 ECU's can be re-programed to '99 down "efan on" to give engine cooling a head start.

Wow.ok it is very confusing with everything I have read on the subject. What you just stated does make the most sense though. Thank you. Do you remember where you got the information from? I would like to read more on it.

Folks here share/post info from their FSM's.

Dude you started a thread and you don't read every post,On post #8 i posted a link where you can download the 2000 FSM.

Dude I down loaded it and said thanks right after you posted it. I have read through it and didn't see where it had anything about an Ac switch. Only have a phone though and there is 1970 pages in the manual so please forgive me if I missed something. I read every post in my threads and alot of other threads. Thank you so much for posting that link!!

AC starts at 1862.
Cooling 258.
The blades broke on my fan,and I ordered one from a 96 because it was cheaper,but the plug was different so I cut the plug from mine and spliced.If you need the motor for yours you can have it just pay for shipping.All you have to do is spliced your plug to it.
https://drive.google.com/file/d/0B2C...it?usp=sharing

Prcherokee you have a pm.

Yes, I believe there is a dealer tsb on this reprogramming of the ECU. My ac is broken so my e-fan never comes on (2000). On my mustang, the ac is broken but the e-fan still comes on when I switch the **** to ac. Will the fan still come on if I disconnect the coolant temp sensor on a 2000? Or is there an easier way to test that my fan and circuitry is working properly.

I changed the mechanical fan to an electric fan and added this temperature sensor and the way I did it it activates both fans at 205 or when the ac is on (low speed) and high speed at 195.(2 speed volvo fan).
https://drive.google.com/file/d/0B2C...it?usp=sharing

As a safety default feature, the efan is turned "on" if the connector becomes unplugged from the sensor in the t-stat cover......at least it is on a '98. If the efan is test jumped directly to the battery and the efan runs, I'd think a "no efan" problem would be in the wiring, fuse(s), relay(s), etc. somewhere between the efan and battery.