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Discussion Starter · #1 ·
I had posted this before in ANGF117's thread, on Feb 2, but got no responses, and problem is continuing.... Can anyone help with suggestions, please?

I apologize in advance if this is thread hijack, but it is similar so I didn't think a new thread was needed... A while ago, my '97 4.6L (52,000mi) temp gage started to kinduv "freeze" in the middle of the range, never dropped to cold, engine runs fine so never goes much above center. I replaced the sending unit with a new one from NAPA and for a couple of weeks, all seemed good, needle dropped to bottom / cold position as soon as I started the car, worked up to middle area and stayed there as it should. Lately, it's back to its old trix: usually (once in a while it DOES drop to the bottom / cold position, after sitting all day or overnight, but seldom) doesn't move MUCH, always in the middle, almost never reads cold, even after a weekend of sitting unused. The gague does however move within the midrange. Today, on the way home I noticed it was rising a bit higher than I normally see it (to about opposite 27-29mph, typically just around 25mph, occasionally as low as 20mph on the adjacent speedo), but then it went back down. I was on the interstate, travelling between 65 - 80mph, outside temps were low 70's. When I got home, I popped the hood, and noticed the radiator fan only running when the A/C compressor kicked in (dash knob was set on MaxAC, temp at about 8:00 position, cabin fan at lowest setting. Question: should fan at radiator run constantly when MAX A/C setting is selected (or def or floor/def, or plain AC .. iow, anything but 'floor')? Or only when compressor kicks in? Iow, is the radiator fan activated by the mode selector knob on the dash or by the compressor switch under the hood?

PS -- stealership replaced plastic intake with new one with aluminum crossover back in early November, new Tstat, "valley hose," & cooling system was flushed & pressure tested after, no problems noted, and car runs great, never overheats, all fluids fresh & full to specs, just PITA dash temp gauge behavior!!!

Any ideas??

:confused:
 

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If the dealership did all that and its still acting funny, I would possible try maybe a new cluster. Maybe the gauge is bad. Go to the junkyard.

Maybe someone else here may have an idea or possibly had the same situation.
 

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Discussion Starter · #4 ·
Richard Dalkranian said:
If your temp gauge is bad I have a spare I will send it to you for shipping cost.
Richard.
Thanks for the very kind offer, and I just may take you up on that, but I would like to verify the cause of the problem before just throwing parts at it ( I may have already violated that concept by installing a new sender, perhaps unnecessarily). I'm gonna try today just pulling the plug off the sender, start it up, see if the needle drops to cold. I would think the problem is more likely in the wiring, and all day yesterday, the needle was responding within the "warm" range, just doesn't drop to "cold" after sitting overnight, so I know the needle / gauge is not totally dead.

Can anyone tell me if the radiator cooling fan is activated by the a/c clutch switch or by the dash mode selector knob? When the knob is set to "Floor" or "Panel" it runs only when the engine gets warm enough to call for it, then shuts down when things cool off, seems just like I would guess it ought to. It also runs when the a/c compressor kicks in, not continuously when the dash knob is set to one of the modes that calls for a/c operation, so it would seem...... Anyone?

Thanks!
 

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My T- Bird was stolen several months ago, but as I remember the fan was tied in to the compressor circuit, when ever the compressor was running the fan would go to high speed. You might try first removing the sender lead, then grounding it. That should cause the needle to go from cold to hot pretty fast. or from Hot to Cold.
Richard.
 

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maybe try another temp sending guage. maybe it was a wrong kind that u got. i remember once i wanted a part from autozone or somewhere and the part that they had was not the right part for the car. maybe buy another sending unit from another parts store and see what happens
 

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Try this. Unplug the temperature sender on the passenger side of the intake manifold, then turn the key on and look at the gauge. It should be pegged at cold since the circuit is open. Now, go out and get a paper clip and jump the two terminals of the sender. Now go and look at the gauge again. It should be pegged on hot or at least very high. If this little test works out, then you know the gauge is fine and the problem is most likely the sending unit. If it doesn't function as described, then you either have a bum gauge or faulty wiring.

As far as the cooling fan goes, there are two different sensors on the car that will activate it. One if the coolant temperature sensor (which is not the same sensor that feeds info to the gauge, btw). If the temp gets too high, the PCM will kick on the cooling fan. If the coolant temp is below 220* F and you go above 45 mph, then the cooling fan will shut off. Also, the fan will kick on when the climate control selector knob is in any of the following positions: MAX A/C, A/C, PANEL & FLOOR, FLOOR & DEFROST, and DEFROST and the A/C clutch is engaged.
 

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Discussion Starter · #9 ·
Thanks, I think those are the answers I needed, will try those simple tests, should be easy enuff even for me!!

I appreciate all your help, guys!!

:cool:
 

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love the forum and search function

I was having problems with my Temp gage not working, replaced both sending units and still nothing. I was thinking the actual gage or wiring is bad. Searched the forum and found the post advising to discounted the waring harness should read zero - makes sense no contact. the next step was interesting - hot wire the harness with a paper clip should read totally hot if gage/wiring is working. That is exactly what happened.

Time to get a new sending unit.
 

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I've found that if you need to look at the dash while you do stuff under the hood, you can use a video camera and monitor to watch the dash.

I set up a camera focused on the gauge I'm looking at, and set a monitor beside the car.

Works great for checking brake lights too. :)
 
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