over heat at idle-making sense of my search results

[RyanM]

ok, 96.5, new radiator 195 TSAT and fresh 50 50 mix. the aux fan is not coming on unless i got the Defrost or ac on. i searched and saw that this is my temp sensor not working right (the one on the tstat housing). the sensor has been replaced before. at idle for about 10 minutes the temp will go past the 3/4 line and i put the defrost on, fan kicks on and it will drop. should i replace the temp sensor and see if that works, or hotwire the plastic fan to a switch, or make a switch and keep the sensor hooked into it? i also thought it may be the ac clutch. any input is appreciated.

[carnuck]

Sounds like they put the wrong sensor in or damaged it in the process.

[RyanM]

yea, all i saw was a record of it from previous owner, i replaced the hoses and radiator and water pump and TS when i bout it. i got a 96 sensor from advance, wrong connection, im gonna trade it for the 97. hopefully this is the last step in my struggle to cool this thing down(besides the aux switch im going to add later)

[Saudade]

The sensor usually just completes the circuit to the fan. Try jumping the connector on the harness and see if the fan comes on. If it does, then the sensor is likely bad. You can also connect an ohm meter across the sensor side of the connector. When the temp gets up as high as it has, you should show continuity.

If jumping the harness end does not turn the fan on, check to make sure one side has 12v.

[Wayne Sihler]

ok, 96.5, new radiator 195 TSAT and fresh 50 50 mix. the aux fan is not coming on unless i got the Defrost or ac on. i searched and saw that this is my temp sensor not working right (the one on the tstat housing). the sensor has been replaced before. at idle for about 10 minutes the temp will go past the 3/4 line and i put the defrost on, fan kicks on and it will drop. should i replace the temp sensor and see if that works, or hotwire the plastic fan to a switch, or make a switch and keep the sensor hooked into it? i also thought it may be the ac clutch. any input is appreciated.

It should not overheat on a 10 min idle.Even with the engine at opperating temp it should take w a y longer for it to reach the temp required to turn on the aux fan.Take a look at the clutch fan,or better yet replace it if its over a couple years old.
Wayne

[RyanM]

well 20 minutes i guess, the temp will just climb, no fan kick in, until i turn on the defrost or ac. ill post what it does tomarrow when i get another temp sender

[8Mud]

I haven't had to mess with the temp. sensor in my wifes 96 yet. I'm fairly sure there are two, one in the thermostat housing, that tells the computer to turn on the fan and another for the the gauge. If the sensor doesn't get it done, it may be a corroded connector. The sensor is just a thermistor, that works with fairly low voltage. The resistance changes with the temperature (in the old Renix the resistance raises as the temerature goes down, I don't really know if the 96 is the same or not). A dirty, wet, oily connector can mess with the values pretty quick.
Jumping anything to do with the computer is risky. As well as piggy backing 12 volt switches into the system.
I'd guess you have a bad fan clutch. The wifes 96 will over heat if it idles longer than 15 minutes or so (in warm weather) and the aux fan kicks in. It didn't used to do that, I'm going to replace the fan clutch (it's still the original/ten years old).

[langer1]

Some things to think about.
The AUX fan will only run when your near over heating, it's not normal for it to come on accept with the A/C.
There are two temp senders, one is for the computer and one is only for the gauge.
If the one for the gauge is wrong (Reading 250 when the temp is only 200) your fan will not be running.

[RyanM]

update, new sensor in the TSAT housing, had to use a 97 sport partnumber to match mine on a 96. oh well it fit and now the aux fan kicks in right at 215, im happy now

[dmillion]

Does it cool off when you start moving? Does it stay cool if you sit in one place, but keep the engine revs up?

Heating up when sitting still, and then cooling off when you start moving, is the classic symptom of a bad fan clutch.

[RyanM]

yes it does, but now the fan comes on and cools it, fan clutch will be next