Junkheep

Hey guys, got a question about my electric fan. I have a 93 sport with the 4.0. Just got the head put back on, and now the electric fan doesn't kick on. It kicked on last night, but every other time I've driven it so far it doesn't kick on. At what temp are they supposed to kick on? And how would I go about testing it? Yes, it is plugged in lol. Thanks in advance.

RatchetMaster10

I'm not sure of the temp the fan should kick on off the top of my head. I will
check at work in the morning and get back to you on that. Check fuses first and make sure there isn't a blown fuse for it. If those are good you may have a bad fan or an input problem such as a faulty coolant temperature sensor

djb383

On at 218F.

RatchetMaster10

I'm seeing on at 190. In a few ill post a repair/diag on it

RatchetMaster10

Also the fan circuit is capable of setting a code in the PCM that will not always turn on the cel. Maybe run by an oriellys or other tool store that has an obd1 capable scan tool with the jeep connector and scan it for codes. If you have a code that can make diag much easier

djb383

Hum, something seems wacked......gauge, signal to fan, something. FSM says 218F is efan on temp.

Junkheep

I'm thinking it may be the coolant temperature sensor. That's the little one towards the back of the head correct? Replaced that before the head went back on. Now, the fan has only kicked on once, and it has been well over 190 and 218. I will check fuses here in a minute.

djb383

Temp sending unit in back of head is for the dash gauge only.....coolant temp sensor in the t-stat housing is for the ECU and efan. Might want to verify efan on temp with temp gun pointed at the t-stat cover. Dash gauge could be wacked.

RenegadeT

to check the fan, unplug it, stuff a heavy gauge wire in each cavity, then touch them to the battery posts. I usually hold the first wire to one post firmly, then touch the other wire to the other post.

and djb383 got it right, unplug the coolant temp sensor on the tsat hsg, the aux fan should kick on.

RatchetMaster10

Agreeing with the stuff being said. I was not able to get the diag page copied on my phone to post for you, sorry man