Electric fan keeps turning off and on

99 XJ Sport, 4.0L, 4wd, 130k miles.

When the engine gets hot or when the AC/def is on (the times when the electic radiator fan ought to be running), the fan will come on for a couple seconds, then turn off, then back on, and off. It will keep doing this, never staying on (or off) for longer than a few seconds.

Is this a bad fan relay or something?

I found on CherokeeForum, a post from several years ago which says low refrigerant could cause this.... but wouldn't that only apply for when the compressor is on, not for when it's just running hot?

If it's cycling off and on, like on for a few seconds once or twice a minute?
If so, the fan will kick on any time the engine temp reaches or exceeds 218.
It'll kick off when the temp is below 218 again, and on again when it's over and so on. I always looked at it cycling as a good thing, meaning my cooling system was working well.
It also kicks on when running the a/c to help a bit with the condenser.


Personally I get worried the few times that the E fan has stayed on constantly which to me means coolant in rad and block have equalized (coolant system is past 100% duty) and the temp starts slowly climbing because.....:explosion......:smsoap:......:repair:

FWIW My 96 and the other 2 XJs (96 and 95) I've had have all cycled off n on as well while running hot.

They have also cycled with the AC if it wasn't crazy hot (under 90) and the engine temp was hovering around 215-220. Sometimes the e fan would run constantly if it was crazy hot out (90+).
Always assumed it was normal since all the ACs were fully charged or almost full..