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loeber
01-25-2005, 06:32 PM
I have a '99 GT. I noticed it was shooting hot water/coolant from the resevoir. At first I thought it would be the water pump. Replaced it, still doing it. Then I replaced the thermostat, no luck still doing it. I started paying closer attention and it looks like the radiator is sending hot water to the reservoir? Then I noticed that the temp read 3/4 hot and the fans were not turning on. I turned on the AC and the fans came on and the temp dropped, but as soon as I turned off the car the fans shut down (The car was still hot, and I thought they were supposed to stay on for a while).

Does anyone have any idea what the problem is? I'm thinking of taking it to the dealer, but I would like to know if there is something I can try before spending big $$$$.

loeber
01-26-2005, 08:11 AM
Anyone?? Any advise??

NorKoastal
01-26-2005, 09:46 AM
Add more coolant to your mix.. I had too much water in my mix and my car acted like that..

loeber
01-28-2005, 06:24 PM
Thanks NorK, I tried that today and no luck. I just bought the temp sensor and will try that next.

Any other suggestions??

loeber
01-29-2005, 11:41 AM
Just changed the coolant temp sensor, still not working. Someone told me to check the cluster for the fans. Does anyhone know where to look?

infiniteslip
02-03-2005, 08:46 PM
loeber, did you figure out the problem? Same thing is happening to me right now...engine starts to overheat at idle and low speeds, then coolant sprays out of the overflow. No fans either unless i turn on the air. Everything else works fine, heater is ok, temp ok at highway speeds and ok at low speed with a/c on. Thought it might be the coolant temp sensor also. Don't know what else controls the fans???

Any info, please post.

loeber
02-04-2005, 10:35 AM
This is what I did and it seemed to have fixed the problem:

Changed the reservoir cap.
Flushed the system entirely.
Burped the system.

It seemed to have fixed the problem. I also read that the computer is set to kick on the fans when the coolant temp hits around 220-230 then shut off when the temp get to 190. If you turn on your A/C it overrides the settings and turns both fans on regardless of the coolant temp.

I would like to have my fans come on before temp gets to 220-230, without installing a switch. I just don't know how.

Also double check to make sure you have no air in the system as that will also cause you to run hot. Let us know what happens.

infiniteslip
02-04-2005, 12:50 PM
hmm, i flushed the system first, then noticed the bad cap, so i replaced that....still runs hots at idle. What did you do to burp the system? I'll try today or tomorrow, for now just running with the A/C on. Thanks for the help.

Black Z28
02-04-2005, 02:24 PM
your coolant should be a 50/50 mix... also, if your leaking coolant anywhere, its going to make it overheat. if you're having problems with overheating, turn your heater on. turning on your AC will make the car heat up, since you'll be making the condenser hot.

infiniteslip
02-04-2005, 08:23 PM
yeah, whose grand am isn't leaking coolant somewhere?? ;-) noticed that last year, gradually loosing coolant over a period of a few months......leaky intake manifold gasket and brown sludge in the coolant. But no coolant in the oil...yet. So I flushed the system and prayed for the best until the loan was low enough to trade it in. Well almost a year and a half later, (can u believe it?), suddenly it's spraying coolant out the overflowed.

When I spun off the resevoir cap, it came off in two pieces and one of the o-rings was out of place. The o-ring was pretty big and didn't seem to fit anywhere right so I put it in the second from the bottom groove and replaced the cap figuring that she was finally biting the dust. So I flushed the whole thing again and cleaned out the tank again which had a sticky level sensor, put it all back together again and still spraying coolant. But....it does not overheat at speed, only at low speed and idle. The heat works and to the best of my observations, the system isn't plugged anywhere. Then I read somewhere about someone's fans not kicking in, and sure enough, mine don't kick in even as I watch the temp go up and the coolant level rise, to the point where the coolant is hot enough to start spraying out. So if it's not overheating at speed, coolant is flowing throught the system, it's not clogged (right?), the thermostat is ok, the heater is ok, probably needs a new resevoir cap since the old one keeps coming off in two pieces. So I got a new cap, hopefully the right one (autozone says it is #7046-15psi). Dramatically improved the situation but still overheats at idle with temp gauge about 215-220, starts venting coolant again. And NO Fans, unless i turn on the A/C. Then everything cools back down again and coolant level begins to drop. So it seems to me that the fans are the magic key, but why won't they turn on. The only thing that is left is the coolant level sensor by the thermostat. Right??? I'm not sure if they are controlled by their own switch/sensor or the computer.

So my daily commute of 45 miles requires me to turn the a/c on to activate my fans until i get on the freeway, then let her suck in the breeze until I get back off into Tampa where I have to turn on the A/C again. If I do that, everything's cool (haha funny). So I don't think it's anything major. I didn't have time to play with it today, but will tomorrow afternoon. Maybe my coolant's diluted after refilling a few times, could be. Doesn't the air come out of the system by itself under pressure? Didn't have any probs last time I flushed.

Any opinions on the coolant temp sensor, what does it actually do? I know that cap had a lot to do with it, but the oil in there isn't helping any of the sensor either I'm sure.

Crap, only $2000 left, just didn't want to hassle with a new car/new loan right now. Sick of payments. Hopefully she lasts just a bit longer. I love this car. Got my stereo/alarm system in (which i will say is a bitch to install in this car), front/rear swaybars, Bridgestone Potenza RE950 tires....she loves the corners. But I also have a few beauty scars from the years, one from a Hummer H2 OUCH. Oh well, she's still my baby....been through a lot together. Thanks for the help everyone. Peace.

andrewe77
08-17-2006, 09:51 PM
I have the same problem. Did you ever figure it out?

timka86
08-18-2006, 08:00 AM
I have the same problem. Did you ever figure it out?


http://www.grandamgt.com/forum/showthread.php?t=61398

look at that thread. The computers for some reason have an error. and you gotta find someone with DHP tuner to help you. Mark(lvemy3100) fixed mine, but he's in IL, and you're in TX.
ask around.

lvemy3100
08-18-2006, 08:27 AM
actaully I will be in SA TX saturday the 19th.... if you would like I can try to look at it.... email me at mkpracing@aol.com

andrewe77
08-18-2006, 02:15 PM
I'm not the OP and I live in MO.

I can't see how it can be a computer problem because my car never had an overheating problem until the past year.

Maybe the cooling system has degraded to the point that the temperature setpoints for the fans in the PCM are too high so it reaches the boiling threshold earlier than it used to?

timka86
08-18-2006, 05:16 PM
I'm not the OP and I live in MO.

I can't see how it can be a computer problem because my car never had an overheating problem until the past year.

Maybe the cooling system has degraded to the point that the temperature setpoints for the fans in the PCM are too high so it reaches the boiling threshold earlier than it used to?


well think what you want but somehow or other, the one setting, something about class II fan turn on, gets messed up, or stops working after a while. there a bunch of people that have this and it doesn't happen right away. It's like the computer forgets to turn the fans on after a certain point in life.

The class II fan turn on only has two settins. Either on or off, and the stock setting wouldn't turn the fans on, and we were monitoring it with digital realtime temp reading. and it went past the turn on point and the fans wouldn't budge (unless of course the A/C was on)

Sprucegagt
08-20-2006, 10:53 PM
Stock cooling fan turn on points:

stock 00 fan 1 turn on temp is 223*F and fan 2 is 232*F

Fan 1 will start first at low speed. Normally so low that you won't hear it. When fan 2 starts both fans run at high speed. This is when you will hear them.

If your car has not reached the fan 2 turn on point before then it means your cooling system has degraded. Check the cap first. If its okay then you have bigger problems. Possibly a partially plugged radiator.


Tim his problems are not PCM related.

westpak
09-03-2006, 03:25 PM
Any other solutions?

I just ran into the same issues except that the AC is also not working, the clutch engages but no cold air.

Otherwise the same thing, the temp slowly climbs until the coolant overflows and no fans, the only way is to disconnect the coolant temp sensor, then there is no temp indication in the cabin but the fans run all the time, either way no ac.

timka86
09-04-2006, 07:44 AM
you guys, no joke, but you guys stole the words out of my mouth when you said what's happening to your cars with the overheating and fans not coming on.

the PCM is exactly what the problem is. I spent hours one day testing all the wiring, relays, and hotwiring the fans directly to the battery and everything worked like it was supposed to, but when i get the car started and running for a while, they wouldn't turn on unless i turn my A/C on.

I had done a total and complete engine overhaul. replaced the pump, sensor and it was still happening to me. and the way i fixed it, well Mark fixed it, is the class II fan turn on, it's a setting in the PCM and for some unknown bizzare reason the stock, that's right, stock setting stops working. so just for kicks any of you with this problem that can go to the A-town meeting next weekend and have mark hook up his DHP tuner to you car and change that setting.

and the worst that could happen is that it still doesn't work, but you attended a meet, got some food, and got to hang out with your GA buddies.

timka86
09-04-2006, 07:48 AM
Stock cooling fan turn on points:

stock 00 fan 1 turn on temp is 223*F and fan 2 is 232*F

Fan 1 will start first at low speed. Normally so low that you won't hear it. When fan 2 starts both fans run at high speed. This is when you will hear them.

If your car has not reached the fan 2 turn on point before then it means your cooling system has degraded. Check the cap first. If its okay then you have bigger problems. Possibly a partially plugged radiator.


Tim his problems are not PCM related.


my 00 GA GT when fan 1 is on, both fans turn on at low speed, and that's consitant with the wiring, cuz they're wired in series.
when fan 2 turns on, they work on separte circuits (parallel) at high speeds.
this might vary from year to year, but you said 00 so i'm just clarifying.

Sprucegagt
09-04-2006, 09:29 PM
my 00 GA GT when fan 1 is on, both fans turn on at low speed, and that's consitant with the wiring, cuz they're wired in series.
when fan 2 turns on, they work on separte circuits (parallel) at high speeds.
this might vary from year to year, but you said 00 so i'm just clarifying.

Your right. I was speaking in terms of PCM usage. PCM defines it as Fan 1 and Fan 2 even though they are not individually controlled.

jorge69i
01-01-2007, 06:23 PM
Hello,
I have a 99 Grand Am GT and I have a problem similar to a lot of the people on here:
It is over-heating because neither fan is coming on.
The thing that makes mine different is that I am unable to get the fans to turn on. . . even if i turn on the A/C.

I would like to try and by-pass the "fan switch" as others have suggested, but I'm not sure where it is located. Can someone please describe (or better yet, provide a picture of) where it is?

I would also like to hear of any other things that I should try.
Thanks,

George

Sprucegagt
01-01-2007, 10:30 PM
I would check both the underhood fan relay and fuse. Both are located in the underhood relay center / fuse box.

jorge69i
01-01-2007, 11:32 PM
I would check both the underhood fan relay and fuse. Both are located in the underhood relay center / fuse box.

Thanks.
I already looked at the fuses and they're good. I guess i can just pick up a new relay tomorrow and try that to see if it will work.

The weird thing is that there is a seperate fuse and relay for each fan. (Both for Fan#1 and both for Fan#2.)
I guess i was thinking that it would be weird for both relays to blow at the same time so i was looking for a "shared" part.

Then again, what do i know. I'm a computer guy, not a car guy. :s
I'll check out the relays and let ya know.
Please let me know of any other things to check.

jorge69i
01-02-2007, 04:38 PM
I have good news and bad news.

First the good news:
I found the fan switch. I must say that it's amazing how much easier it is to see things in the day. I found the temp sensor in less than 30 seconds when i was looking at it outside. :blushing:
In case someone needs help finding it, I've attached a picture.

And the bad news:
The fans still don't turn on.

In addition to the new fan switch, I got a new radiator cap.
I have also tried switching relays with ones in my fuse box that i know are working.

Please let me know of other things to try.

Sprucegagt
01-03-2007, 06:16 AM
How hot do you allow the engine to run? I ask because the stock fans don't run at high speed until 230*F.

coupe
01-03-2007, 06:30 AM
Im in the same boat.
My fans dont come on at all.
Only when i turn the car off and thats becuase of my retune.

dna_dan
01-03-2007, 02:28 PM
Isn't the original post on here pretty old? Is that person still having issues? I was thinking a stuck thermostat might cause a backup in the reservoir once the liquid expanded.. I think this person is already gone.

In regard to the fan comments, mine comes on really late. I don't think it's the low one either. It seems to be all on or all off. I never have low speed or one fan, them both fans come on.

Something is definitely not right with the fans on our cars.

As a side-note, when I did my LIM change I also moved to another coolant. After I did the radiator flush, not much crap came out from the flush. I could still see it in the reservoir though. I assumed this stuff wasn't going to dissolve because it was like gum. I replaced the coolant reservoir to see if the new coolant (prestone extended life) would do the same thing. It's been about a year now and the coolant still looks new as the day I put it in there. However, the damage from the crappy ass DexCool is already done. My radiator has a decreased efficiency due to the dexcool gumming it up. This could also be another caveat to a lot of heat issues as our cars have aged. I know many people have already switched the coolant, but I was unable to get a complete flush when I tried to clean out the Dex doodie.

jorge69i
01-03-2007, 08:23 PM
How hot do you allow the engine to run? I ask because the stock fans don't run at high speed until 230*F.

My engine got up above 230 and neither fan came on. However, it was also low on coolant at that time. I'm not sure if that has anything to do with the problem or not. . . Either way, turning on the A/C should cause the fans to come on, right?

Earlier this week, I topped off the coolant and "burped" it.
The fans still aren't coming on with the A/C and i haven't had to drive in stop-and-go traffic the last couple of days, so i'm not sure if it's still over heating.

jorge69i
01-03-2007, 08:29 PM
Isn't the original post on here pretty old? Is that person still having issues? I was thinking a stuck thermostat might cause a backup in the reservoir once the liquid expanded.. I think this person is already gone.

In regard to the fan comments, mine comes on really late. I don't think it's the low one either. It seems to be all on or all off. I never have low speed or one fan, them both fans come on.

Something is definitely not right with the fans on our cars.
....



You're right. That person is gone.

I'm sorry. I should have probably started a new thread, but i found this one and the problems seemed very similar. . .

Someone please let me know if i should just start a new tread anyway.

Sprucegagt
01-03-2007, 08:35 PM
My engine got up above 230 and neither fan came on. However, it was also low on coolant at that time. I'm not sure if that has anything to do with the problem or not. . . Either way, turning on the A/C should cause the fans to come on, right?

Earlier this week, I topped off the coolant and "burped" it.
The fans still aren't coming on with the A/C and i haven't had to drive in stop-and-go traffic the last couple of days, so i'm not sure if it's still over heating.

The fans should automatically come on when the A/C is turned on. If your sure the fuses and relays are good, then you have to have a broken wire or bad connection somewhere. I know in my underhood fuse box, I can get water in it. Resulting, in my case, the fuel pump relay acting up. But the other relays are in the same area, so either one can cause the problem.

jorge69i
01-07-2007, 10:56 AM
The fans should automatically come on when the A/C is turned on. If your sure the fuses and relays are good, then you have to have a broken wire or bad connection somewhere. I know in my underhood fuse box, I can get water in it. Resulting, in my case, the fuel pump relay acting up. But the other relays are in the same area, so either one can cause the problem.

Cool, i'll check into that.
Can I get one more quick thought to help narrow down my wiring search:

Am i correct in assuming that the sensor that I replaced is what the temp gauge in my car reads from? And if so, the wiring from the sensor to the computer and gauge must be good, right? So that means my problem should be between the computer and my fans, right?

Sorry. These are probably dumb questions to you guys.
Thanks!

jorge69i
01-07-2007, 05:18 PM
OK, I figured out a way to test my theory above.

1. Start the car and let the needle on the temp gauge move up a noticeable amount. (Maybe 170 or so.)
2. Turn the car off and disconnect the sensor.
3. Start the car again and check the gauge.

The result with the temp gauge was i expected: The needle didn't move back to 170. This confirms that the gauge uses the sensor that i replaced and the wiring is intact.

HOWEVER. . .
Something else happened when i did this that i didn't expect. A few seconds after i started my car, I heard a "whooshing" sound. I got out of my car and looked in the engine bay. Yup, you guessed it: Both fans were spinning at high speed.

I can only assume that this is some kind of "safety" feature. (IE: If the car doesn't know how warm it is, it will turn the fans on to prevent "possible" overheating.)

I plugged the sensor back in and the fans soon turned off. I then turned on the A/C, but unfortunately, the fans did not come on.

I should also probably mention that I tried plugging the sensor in with the car both "on" and "off". (Yeah, i know it's not a good idea to plug things in when the wires are "live" but i was hoping that i might "trick" it into working.)

Please help me out guys. . . What am I missing?

andrewe77
01-07-2007, 05:47 PM
OK, I figured out a way to test my theory above.

1. Start the car and let the needle on the temp gauge move up a noticeable amount. (Maybe 170 or so.)
2. Turn the car off and disconnect the sensor.
3. Start the car again and check the gauge.

The result with the temp gauge was i expected: The needle didn't move back to 170. This confirms that the gauge uses the sensor that i replaced and the wiring is intact.

HOWEVER. . .
Something else happened when i did this that i didn't expect. A few seconds after i started my car, I heard a "whooshing" sound. I got out of my car and looked in the engine bay. Yup, you guessed it: Both fans were spinning at high speed.

I can only assume that this is some kind of "safety" feature. (IE: If the car doesn't know how warm it is, it will turn the fans on to prevent "possible" overheating.)

I plugged the sensor back in and the fans soon turned off. I then turned on the A/C, but unfortunately, the fans did not come on.

I should also probably mention that I tried plugging the sensor in with the car both "on" and "off". (Yeah, i know it's not a good idea to plug things in when the wires are "live" but i was hoping that i might "trick" it into working.)

Please help me out guys. . . What am I missing?

At this point it's probably a bad PCM.

Sprucegagt
01-07-2007, 06:59 PM
Cool, i'll check into that.
Can I get one more quick thought to help narrow down my wiring search:

Am i correct in assuming that the sensor that I replaced is what the temp gauge in my car reads from? And if so, the wiring from the sensor to the computer and gauge must be good, right? So that means my problem should be between the computer and my fans, right?

Sorry. These are probably dumb questions to you guys.
Thanks!

Correct. The sensor you replaced is the only coolant temperature sensor on the engine. But it does not directly control the fans or gauge. The only thing it does is send it's signal to the PCM. The PCM then sends information to the gauge and determines when the fans will turn on. But the gauge is not very accurate. So don't assume that if it goes 3 "notches" over 200 that it means 230.