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Help. please. Lacrosse engine fans keep running with high temp warning.

oldteach

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For the second time in eight months, when I started my 3.0 Buick Lacrosse, a warning stating that the AC is shut down due to engine overheating and also both fans will not stop running, even when I shut the car off, for at least 10 minutes. The strange thing is that the temperature guage stays at full cold along with the engine actually being too cold instead of too hot....even after running the car around town...and a code for Engine UNDER temperature(due to the fans never shutting off the whole time) is stored......AND the air conditioner actually does work just fine. Anyone ever have this happen to them or can share what detective part is causing this?
 

HotZ28

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I would first check the coolant temp sensor with a scanner to determine if it corresponds to the gauge reading. You may have air in the system, but you need to do some further diagnostics.
 

yesthatsteve

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'13 LaCrosse eAssist
I would first check the coolant temp sensor with a scanner to determine if it corresponds to the gauge reading. You may have air in the system, but you need to do some further diagnostics.
+1. Coolant temp sensor is the best place to start.
 

Mad*Max

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what year is your car, where is the coolant level at (hot and cold?)
 

oldteach

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what year is your car, where is the coolant level at (hot and cold?)
It stays on cold because the twin fans run the entire time the car is on, and keep running for 15 minutes after the car is shut off. The air conditioner actually runs fine , even though the warning says" air conditioner shut-off due to engine overheating" ...(neither is true). This happened 8 months ago, the tech unplugged various connectors until the fans finally shut off and everything went back to normal. Then suddenly this past week it happened again after 8 months of being OK.. I am wondering if it is some sort of central control processing(main one), because this time it was also preceeded by no display on the main screen and assorted push buttons, like the seat warmer, turning on by itself....which lasted 5 minutes or so, before returning to normal. This is weird stufff and the car is at the dealer now, but they are having a hard time finding the cause. Has this ever happened to anyone else? It is a 2010 LaCrosse 3.0 CXL. The car is actually too cool, not overheating at all. I am afraid to drive it because the fans continuing to run can deplete the battery.
 

HotZ28

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Usually, there is only one, or two MASTER TECHNICIANS at the dealers. I would request his/her advice/expertise before leaving. Have you tried disconnecting the negative (-) battery cable for a few minutes, then reconnecting to see if the same problems exist?
 

Mad*Max

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like HOTZ28 says, try disconnecting the battery as it sounds like a software glitch which these cars tend to have a lot of...do you know anybody with a sophisticated scanner that can control the car when connected, maybe they can check the fan settings for you?

It stays on cold because the twin fans run the entire time the car is on, and keep running for 15 minutes after the car is shut off. The air conditioner actually runs fine , even though the warning says" air conditioner shut-off due to engine overheating" ...(neither is true). This happened 8 months ago, the tech unplugged various connectors until the fans finally shut off and everything went back to normal. Then suddenly this past week it happened again after 8 months of being OK.. I am wondering if it is some sort of central control processing(main one), because this time it was also preceeded by no display on the main screen and assorted push buttons, like the seat warmer, turning on by itself....which lasted 5 minutes or so, before returning to normal. This is weird stufff and the car is at the dealer now, but they are having a hard time finding the cause. Has this ever happened to anyone else? It is a 2010 LaCrosse 3.0 CXL. The car is actually too cool, not overheating at all. I am afraid to drive it because the fans continuing to run can deplete the battery.
______________________________
 

douger

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341
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Fort Wayne, Indiana
Buick Ownership
2012 Buick LaCrosse Touring
It stays on cold because the twin fans run the entire time the car is on, and keep running for 15 minutes after the car is shut off. The air conditioner actually runs fine , even though the warning says" air conditioner shut-off due to engine overheating" ...(neither is true). This happened 8 months ago, the tech unplugged various connectors until the fans finally shut off and everything went back to normal. Then suddenly this past week it happened again after 8 months of being OK.. I am wondering if it is some sort of central control processing(main one), because this time it was also preceeded by no display on the main screen and assorted push buttons, like the seat warmer, turning on by itself....which lasted 5 minutes or so, before returning to normal. This is weird stufff and the car is at the dealer now, but they are having a hard time finding the cause. Has this ever happened to anyone else? It is a 2010 LaCrosse 3.0 CXL. The car is actually too cool, not overheating at all. I am afraid to drive it because the fans continuing to run can deplete the battery.
All of that stuff runs through the engine control module. What another poster suggested is your best course of action: find out what's going on with the ECM by plugging in a scan tool. It doesn't make sense to throw parts at it in the hopes of fixing it.

Here's what you can try for free: find the coolant fan relay. It should be in the under hood fuse block. Pull it and tap it on something, then put it back in. Put it back in and see if the fans shut off properly. If they're running excessively, it's possible the relay contacts are sticking. There may be two relays.
 

oldschool

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'03 Buick LeSabre, '07 Allure CXL
Or pull the relays and leave the fans disabled until you find the actual problem. As long as it's cool in your area and you feel you don't need the fans then it's all good until the cause is found.
 

oldteach

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Well, my car is still in the dealership to Monday being repaired . It threw a code for a stuck thermostat, and the wate rpump was leaking, and the battery had a bad cell....all were replaced and covered under my extended warrantee, except the battery. I hope this fixes it. The interesting thing is this "AC shut down due to overheating warning, with a coolant meter reading of zero(it is actually not overheating...it is underheating due to both fans refusing to turn off, even for 15 minutes after the car is shut-down....which kills the battery pretty quickly" is a real GM in general issue....it happens in trucks, vettes, cruzes, Buick LaCrosses, Caddy's, etc. The web search for this problem goes on for pages, is identical to my problem, and in some vehicles it returns to haunt their owners for years. I sure hope what they just did fixes the problem. I will let you know if it doesn't.
 

bobby49

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1. The car: what model, year, and engine?

[I went back a few weeks and found the post. 3L engine.]

2. You say that it threw a code for a stuck thermostat. What was the code?
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Last edited:

tomtella

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30
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Wolcott, CT
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2010 LaCrosse CXL AWD
I am having the same problem with my 2010 LaCrosse: The coolant gauge goes to zero, a message pops up that says the AC is stopped because of high engine temperature and the radiator fan runs for 10 minutes when I shut off the engine. There is nothing wrong with the cooling system. After a few engine starts, it will also pop on the check engine light. After usually 2 days, the problem simply disappears. Then after about 2 to 3 weeks it starts all over again.
And yes, I have replaced the coolant temperature sensor (incidentally, very easy and inexpensive to do).
Anybody know what's going on here?
 

tomtella

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4
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Wolcott, CT
Buick Ownership
2010 LaCrosse CXL AWD
I also discovered that even before the check engine light comes on, it does pop up P0128, and the instant you clear that DTC, the problem goes away. But then it laughs at you and comes back in a day or two.
______________________________
 

tomtella

Full Member
30
4
8
Wolcott, CT
Buick Ownership
2010 LaCrosse CXL AWD
Tack000 got it right! The solution to this problem is nothing more than a good old-fashioned failed thermostat. The thing that sent me (and many others) into a wild goose chase is the fact that when the engine fails to maintain a normal operating temperature (in other words, it is too cool), it pops up P0128 which in turn pops up that message that the AC is off because of high engine temperature (which it certainly is not) and also causes the radiator fan to run for 5 minutes after you shut off the car. There is nothing wrong with your cooling system or temperature sensor, you just have to replace the thermostat. The bad news is that it is replaced as an assembly with its housing so it is pricey as thermostats go, but the good news is that it is easy to replace. This old former mechanic did the job in his driveway in 20 minutes.
 

G-533632

Tack000 got it right! The solution to this problem is nothing more than a good old-fashioned failed thermostat. The thing that sent me (and many others) into a wild goose chase is the fact that when the engine fails to maintain a normal operating temperature (in other words, it is too cool), it pops up P0128 which in turn pops up that message that the AC is off because of high engine temperature (which it certainly is not) and also causes the radiator fan to run for 5 minutes after you shut off the car. There is nothing wrong with your cooling system or temperature sensor, you just have to replace the thermostat. The bad news is that it is replaced as an assembly with its housing so it is pricey as thermostats go, but the good news is that it is easy to replace. This old former mechanic did the job in his driveway in 20 minutes.
I have a 2011 I replaced my thermostat that was 2 weeks ago by the end of first week the message is back up on instrument panel. Maybe with the number of people having issues it should be recalled its ridiculous so many people are having same issue.
 

G-648228

I get the same message when I haven't even been running the air conditioner. At least though I can pull over, turn off the car and in less than a minute the fans turn off and when I start up the car again the message has disappeared. I think its a software problem. The coolant temp sensor is not functioning because of a programming malfunction. The sensor itself is fine as well as the thermostat so replacing is futile. Cars these days need a reboot button or a disk to reset any faulty software.
 

G-73831

I have this same problem however it only happens when it is cool outside. Like 50 degrees once the outside temp is higher it goes away?
 
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