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Discussion Starter · #1 ·
I'm totally stumped...my temp gauge is totally out of whack from normal. it normally sits just before the center point of the gauge. Today on the freeway I just happened to glance down and noticed the gauge was pegged at H. Got off, looked, no signs of overheating. got home, cautiously, and started the checklist. May or may not be related; when starting cold the A/C works fine, but as the car heats up the compressor stops coming on, just blowing normal temp air.

Just for information sake, the water pump, thermostat, hoses, radiator cap, and belts were replaced less than 500 miles ago.

Using a laser temperature gauge--all areas (hoses, thermostat housing, radiator) are in a normal range 160-180 generally, sometimes slightly higher or lower but very consistent.

Bled the system again

Pulled the coolant temp sensor near the bleeder bolt/screw tested it, normal .25 resistance at 194F

Radiator fans work

Is there more than 1 temp sensor? when we pulled the one to check it, the temp gauge still read a temp not at C and as expected check engine light came on (went off after re-installing)

Sitting at idle for 10-15 minutes, the gauge sat at the halfway point (A/C on or off, cycling normally). Went for a drive, got up to highway speed and the temp gauge rockets to near H just after the A/C compressor stops cycling (seems to be ok at lower speeds but that may just be coincidental). Turn off the A/C and the temp gauge drops marginally. Got back and checked temps with the gauge near H and they are all within normal operating.

So, why is my gauge showing Hot but temperature readings are normal?
Help please, running out of ideas.
 

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Discussion Starter · #3 ·
I assume you mean 0.25V at 194F, but that's very low. The ECT should read about 3.5V cold to 1V hot. You have a bad ECT sender.
according to chilton's manual, the ECT sensor for a 91-94 GA16DE engine should read between 0.24-.026 resistance k(ohms sign) at 194 degrees F which it does. 2.3-2.7 @ 68F and 0.14-0.15 @ 230F. As the temp increased the resistance decreased as it should, not saying its not the sensor, but according to the specs its good.
 

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Thanks for clarifying. In K ohms that does sound healthy, but you should check voltage anyway to make sure the system pullup resistor isn't blown and that there isn't a low grade short in the wiring or the cluster. Either condition will pull the voltage down and make it read hot when it isn't.
 

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Discussion Starter · #5 ·
that's why I was wondering if there was a second sensor that sends to the Gauge, I know the the one we checked sends to the ECU. in other readings I see indications of a second one, the book doesn't show one.
we'll check for Volts later, the book shows volts on the 95-96 model GA16DE but only k ohms on the 91-94. not sure how to go about that testnmnjjjjjjjj
 

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ok, super, can you tell me where the one for the cluster is located?
No, I looked through the documentation in Identifix and I can't find a location drawing. I'll take a look in ASIST at work on Thursday if you haven't figured it out before that. SMJ might know if he reads this, he's better with the oldies than I am.
 
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