96 GT Overheating Issues

96redGtB

New Member
Jul 25, 2022
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New here. Just picked up a 96 GT a couple weeks ago. Having some heat problems. Turns out fan isn't running unless AC is turned on. Gets to about the A in normal never hits red. I've seen this discussed In multiple threads but they are fairly old. Since the fan comes on with AC ( not sure if it's low or high speed working , its barely audible but pushing air , I assume means the ccrm is working. Possible ECT? The part numbers are confusing for the sensors since there are two and the sending unit for the gauge seems to work just fine. Will disconnecting a sensor make the fan run? Also is there audible difference between high speed and low? If I leave the AC on and drive so I know the fan is still running it still gets the needle past halfway pushing towards A. If I idle with AC in the driveway until warm it cools down to normal and stays , ac off temp just climbs as fan doesn't run at all. So to me it seems as the only the low speed runs with AC on. I know there is likely a lot of things it could be but just looking for some direction on it. I have burped the coolant system. No intake leaks I'm aware nothing seen at least( it did spew coolant from the back of the intake heater hose on the drive home since I did not know the fan wasn't running and it got too hot. Since I've tested at home the hose has not leaked again as I monitor the temp closely while troubleshooting.
 
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96redGtB

New Member
Jul 25, 2022
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Update . Unplugging the ECT makes the high speed fan come on. So now I know both fan speeds are good. Changed ECT out still same issue. No fans so either air got in and is hitting the sensor saying it's cold still , maybe partial open stuck thermostat?
 

96redGtB

New Member
Jul 25, 2022
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The low speed runs when the AC Is on though, the high speed runs when the ECT is unplugged so both fan speeds appear to work. Definitely an audible difference between the two I found out . I know I'm probably not explaining it well . Thank you for the reply.
 

96redGtB

New Member
Jul 25, 2022
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The fan is not running unless I turn the AC on it goes on low speed , or if I disconnect my ECT the ecu goes panic and turns the high speed on . Without the AC or ECt unplugged no fan actually gets close to L and I know it's hot because it got hot enough to piss coolant through the heater nipple on the back of the intake. Now that I've had it home and been testing it I never let it get that high and it hasnt leaked a drop of coolant since. So it gets hot . I didn't let it over heat and keep driving it to prevent damage. I did a lot of testing and more to do. Fan is fine on both speeds by battery power outside the car as well. I'm thinking now that the previous owner did a coolant flush and didn't burp the system well and I have air near the sensor in the manifold causing it to read wrong and run poorly. Running as if it's cold doesn't turn the fan on. Going to pull hose of thermostat and backfill the radiotor on an incline to make sure there is no air. If that doesn't work I'll start checking some wiring. I appreciate all the feedback and suggestions
 

chrlsful

Active Member
Mar 6, 2021
257
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"...backfill the radiotor on an incline..."
all ways use a fisnell funnel (spelling) when filling a radiator

now leave the radiator cap off & run 10 min/up to temp, to bleed out the air. Ur 'incline' idea is good (additional help for air bleed out). Use cheep IR guage to seek temps around and about the system... 220/40* is danger (idling).
 

96redGtB

New Member
Jul 25, 2022
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Ok will do. When I referred to "backfilling " I was referring to what this guy does in his burping video for 2v


View: https://www.youtube.com/watch?v=xVXLedrbwu0


Pulling the hose off the t-stat, filling the coolant from the hose side not the overflow tank( although I know the overflow tank serves as the radiator cap) . I'll grab one of those kits fr HF and the therm to . Got one down the street.
 

mustystang

Claiming to be an Alpha Chassis
Aug 20, 2022
112
9
18
I've recently been having similar problems. I think I saw that video. I don't think it's necessary to fill from hose, nothing would be that ridiculous to refill a cooling system properly.

Can you upload a pic of your fuse box?

Also, housing unit may be leaking intermittently depending on temp and load conditions. Check out my thread, I basically had a constant blanket on top of my engine keeping it hot with a bunch of parts failing at the same time. Not really sure what started to fail first but basically everything needs replaced. I'd recommend a proper coolant flush by doing it yourself too. I had a shop do one recently and coolant is just as dirty as when I brought it in. Complete waste of money. Also check your hoses and other coolant items. Your water pump may also be corroding and not really working properly. All of these things together make everything worse so it could be a bunch of things at the same time. Upload clear picture of fuse box though too.