Cooling fan not turning off

On a 97 sport. 4.0, aw4, 231 etc

Sometimes when parking it after getting to op temp the aux fan will not turn off and will run until the battery is dead. This is a problem! Where is the temp sender to keep this fan on? Is the the temp sensor on tstat? Also, what else is controlling this system. Obviously a relay, but where is the logic? ECM?

This jeep has 150ish thousand miles but a relatively unknown history. My sister (unfortunately a classic blonde chick) drove this for a couple years and damn near broke everything!!! Since it has been back from her the following things have been replaced: cps, hvac controls, blower fan resistor, blower fan, all fluids, transmission cooler lines, ball joints, unit bearings, brakes and battery.

The following will be replaced soon: steering gear box, battery terminals and cables.

I would like to make this a reliable vehicle again. It just needs some love!

Replace the cooling fan relay. The ecm controls the fan via the relay.

So is it just old and getting "stuck" in the on position?

likely. wouldn't be surprised if the fan was getting old and starting to pull too much current.

Could be. Thanks for the help.

I was having the same issue. I just replaced the relay and hooked it up to a switch inside the cab. Anytime I'm in crazy traffic I turn the fan on. If you do it that way just make sure you turn it off when you turn off the vehicle or get a good battery. Might not matter but I hate when my battery goes dead so I'm a little paranoid

sandyeggoxj said:

So is it just old and getting "stuck" in the on position?

Click to expand...

I'm old, but I usually get stuck in the "off" position.

HA! That's awesome joe. This is actually my little brothers rig. I'm just helping him out. I would expect to see him lurking around naxja soon! I've got a 99 that other than running the aux fan constantly while I'm wheeling doesn't have any major issues. Yet.