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I have a 300c 2.7 from 2005. Recently I have some cooling issues resulting in overheating the engine. Keeping a close watch on the engine temperature I can prevent overheating by turning on the heater and drive with open windows..... believe me..... trying to get somewhere it's not just the car overheating but I'm also in a boiling state :(.

I noticed that the cooling fans won't come on. I connected them to the battery and they do work. My car runs normally at 90 degrees celcius. Now it can go up to 100 and even 104 degrees celcius and still the fans won't come on. I checked the fuse and the relays ans they al seem fine. I did some other testing and I noticed that when I disconnect the connector from the temperature sensor the meters in the car give 0 degrees. To prevent the engine from overheating the car starts some kind of safe mode, and the cooling fans come on and they runs at max. That means that the fans, the fuse, the relays and the computer are all fine.

Can someone please tell me why the fans won't come on running the car in a normal way.
 

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Sounds like something's screwy in one of the car's computers (there are 9 computers onboard).

Perhaps it would be best to hook it up to the StarScan tool to get a proper diagnosis.
 

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Discussion Starter #3
don't have a tool like that i'm afraid. I did checked if the fans are running when i switch on the AC. But they didn't dow anything. Disconnect the temperature sensor again and the fans ran at maximum speed..... anyone?
 

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I believe the 300 fans have 3 speed settings, low, mid and high speed, for the fans to kick in at high speed mode during very severe temps. the fuses, relays, and temp sensor are functioning.

I do not know how many temp sensor the 2.7 has, but hopefully somebody on the board would chime in on that. If, it has more the one, maybe the one that control the low/mid mode is bad.

Have you replaced or drained your coolant recently? Maybe there is air in the system, find out how to bleed the coolant system. Check coolant levels.

When do it overheat, city or highway driving or both?

On my previous cars, I was able to just replace a resistor to fix my, I have no clue if it will be the same for the 300.

Here are some of the common causes of overheating:

1. Head gasket leak, check to see if there is coolant mixed in the oil. See if there a chocolate milk shake substance on the bottom of the oil cap. If not, most likely the gasket is good.

2. Leaking coolant system, hoses pin size hole.

3. Thermostat bad.

4. Temperture sensors, do not know how many the 2.7 has.

5. Clogged coolant system, since you say it flows with the temp setting high, you can rule that out.

6. Heater core valves, should be located near or on the firewall, two holes leading into the engine compartment.

For now thats all I can think of. hope it helps narrow down your issue.

Thanks,
SGBreeden
 

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Discussion Starter #6
I believe the 300 fans have 3 speed settings, low, mid and high speed, for the fans to kick in at high speed mode during very severe temps. the fuses, relays, and temp sensor are functioning.

I do not know how many temp sensor the 2.7 has, but hopefully somebody on the board would chime in on that. If, it has more the one, maybe the one that control the low/mid mode is bad.

Have you replaced or drained your coolant recently? Maybe there is air in the system, find out how to bleed the coolant system. Check coolant levels.

When do it overheat, city or highway driving or both?

On my previous cars, I was able to just replace a resistor to fix my, I have no clue if it will be the same for the 300.

Here are some of the common causes of overheating:

1. Head gasket leak, check to see if there is coolant mixed in the oil. See if there a chocolate milk shake substance on the bottom of the oil cap. If not, most likely the gasket is good.

2. Leaking coolant system, hoses pin size hole.

3. Thermostat bad.

4. Temperture sensors, do not know how many the 2.7 has.

5. Clogged coolant system, since you say it flows with the temp setting high, you can rule that out.

6. Heater core valves, should be located near or on the firewall, two holes leading into the engine compartment.

For now thats all I can think of. hope it helps narrow down your issue.

Thanks,
SGBreeden

But correct me if i'm wrong. But I think it doesn't really matter what the reason is that the engine is overheating. The fans should always come on as soon as it reaches a certain temperature. When you go in the hidden menu you can see what the coolant temp is and it's showing that it just overheating. Still the fans won't come on. Not even when it's getting near the "red zone". But they will run at maximum speed as soon as I disconnect the temperature sensor.
I've read that the fans should start as soon as you switch on the AC. I tried. Still no fan activity.
 

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In order to figure out the problem, you have to figure out what is going on, unless you willing to drop money for parts after parts until you find the bad one. Then yeah, you right.

Just consider diagnosing car problem, like a writing math problem, you have to figure it out in order to get the right answer.

Now back to your issue.

Some of the reasons for the fan not coming are within the list I posted. Yes, I went above and beyond, but thats what I do as a ASE technician.

I missed the part when you stated "you disconnected the temp. sensor and the fan run at high speed". I think you just might have figured out the problem to your car.

I would put in order what to check first to least.

1. Low coolant,

2. Air in the system.

3. Bad temperture sensor (most likely from your statement "unplugging the temp. sensor")

4. Stuck heater valve

As for todays automotive AC's, they will not turn on if the outside temperture is below a certain degree.
Again, I am talking from my previous cars, I only been in the 300 for two weeks.

But all repair are some what universal.

Thanks,

SGBreeden
 

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Discussion Starter #8
In order to figure out the problem, you have to figure out what is going on, unless you willing to drop money for parts after parts until you find the bad one. Then yeah, you right.

Just consider diagnosing car problem, like a writing math problem, you have to figure it out in order to get the right answer.

Now back to your issue.

Some of the reasons for the fan not coming are within the list I posted. Yes, I went above and beyond, but thats what I do as a ASE technician.

I missed the part when you stated "you disconnected the temp. sensor and the fan run at high speed". I think you just might have figured out the problem to your car.

I would put in order what to check first to least.

1. Low coolant,

2. Air in the system.

3. Bad temperture sensor (most likely from your statement "unplugging the temp. sensor")

4. Stuck heater valve

As for todays automotive AC's, they will not turn on if the outside temperture is below a certain degree.
Again, I am talking from my previous cars, I only been in the 300 for two weeks.

But all repair are some what universal.

Thanks,

SGBreeden
No time for the chrysler.... :(, busy @ work, been forced in bed by the flew (not a pretty sight believe me !!!)But......Finally have some time to check the things you mentioned. Get back asap with my findings.
 

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I believe the 300 fans have 3 speed settings, low, mid and high speed, for the fans to kick in at high speed mode during very severe temps. the fuses, relays, and temp sensor are functioning.

Two speed fans: low and high. Unless you count off, then three.
 

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Discussion Starter #10
I believe the 300 fans have 3 speed settings, low, mid and high speed, for the fans to kick in at high speed mode during very severe temps. the fuses, relays, and temp sensor are functioning.

Two speed fans: low and high. Unless you count off, then three.
I'm following the same logic. When something goes wrong and the car doesn't get a temp reading anymore. (meaning I disconnected the temp sensor) The fans start running in high speed. This does mean that the fuses, relays, temp sensor and the rest are working fine.
So far I checked

Coolant level==> OK
temp sensor ==> OK
thermostat ==> OK
No air trapped. Filled it exactly as told in the manual

Still have the same problem. Car temperature goes up. No fan activity. To prevent overheating I'll switch on the interior heater at max. and drive with all the windows open to prevent overheating myself. The engine temperature immediately drops as soon as I switch on the interior heater.
Suggestions anyone? Am I searching in the wrong places. Starting to think it maybe drive belt or water pump related. But that doesn't explain why tje fans won't come on. :(
 

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Woke up this old thread because I'm having a similar issue. Jewel, did you ever find your fan control issue?

Which is to say: HIGH fan does not kick in at idle UNLESS AC is on. The high fan comes on immediately with the AC compressor, even if the engine is not fully warmed up. Temperature reading in EVIC shows as high at 220F, but drops back down to 204...199 with AC (and high fan) on, also at highway speed without AC. So, radiator thermostat, relays, fuses and CAN bus messages to turn on high fan must be working, but whatever sequence tests for temperature without AC on is not doing the proper thing.

This is on a HEMI 5.7 stock.
 

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Woke up this old thread because I'm having a similar issue. Jewel, did you ever find your fan control issue?

Which is to say: HIGH fan does not kick in at idle UNLESS AC is on. The high fan comes on immediately with the AC compressor, even if the engine is not fully warmed up. Temperature reading in EVIC shows as high at 220F, but drops back down to 204...199 with AC (and high fan) on, also at highway speed without AC. So, radiator thermostat, relays, fuses and CAN bus messages to turn on high fan must be working, but whatever sequence tests for temperature without AC on is not doing the proper thing.

This is on a HEMI 5.7 stock.
There are three relays that control the fan(s), all located in the Integrated Power Module (or IPM) in the engine compartment, they are labeled something like "Radiator Fan Control", "Radiator Fan High/Low Control", and "Radiator Fan High". Physically and electrically they are identical. Either the owner's manual has a diagram of their respective locations, or the cover on the IPM has a diagram on its interior side. Identify which they are, and replace each in turn one at a time with another relay of the same type that is known to be good to see if the operation of the fan(s) changes back to normal.

Good hunting.
 

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Thanks, I initially tested each relay for resistance, then tried swapping the 4th relay (power down control) into the other 3 positions - no change, then I bought 4 new relays, tried one at a time, then 2,3, all four - no change.

Since the high fans come on when the AC compressor is on, the relays have to be doing their job because they are the only path to power the high fans.

There has to be something else preventing the FCM from closing those relays on the coolant temperature levels.
 

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Thanks, I initially tested each relay for resistance, then tried swapping the 4th relay (power down control) into the other 3 positions - no change, then I bought 4 new relays, tried one at a time, then 2,3, all four - no change.

Since the high fans come on when the AC compressor is on, the relays have to be doing their job because they are the only path to power the high fans.

There has to be something else preventing the FCM from closing those relays on the coolant temperature levels.
Well then what happened?
 

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Well then what happened?
That post is from six years ago, so, let's see...Russia annexed the Crimea, there were these big terrorist attacks in Paris, the Cubs won the Series, that mass shooting in Vegas, Prince Harry and Meghan Markle got hitched, Avengers Endgame turned out to be the highest grossing movie of all time, and of course, Brexit was last year.
 

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CTCarl it's just great to learn how you sit around watching tv all the time while others must go to work for a living each day.

I just wanted to know cmego's 300 outcome after he went through so much but' since he didnt return we don't know what happened next there?
I was hoping his issue may also be the fix for my friend's 300 having the same issue because it's had everything changed too. I mean everything too, just had head gaskets done 2 weeks ago.
He had the rest here done over last couple months, his water pump/fans/rad/temp sensor/relays/hoses/heater core and thermostat, all this was changed out by (2) mopar steelerships and the p.o.c. still overheats.
So' Mopar cant fix his car either, just keep throwing parts at it is all they do, imagine that?

But it no longer matters because after being stranded yesterday he finally wised up and trading it in on a brand new Lexus.
He had to spend thousands on this 300 just to make it reach 130k miles. Thats quality there!

You can now return to watching the world pass by you on your boobtube... Wow that's exciting...lol
Enjoy it now, your 300 will be down again by next week.
 
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