Radiator fan is running after I turn off the car
11-16-2017, 09:25 AM
#1
Radiator fan is running after I turn off the car
So I had to replace my battery yesterday because it died. It died because the radiator fan is running for up to 20 minutes after the
engine is turned off. I know that''s common on a warm day, but it''s been happening on short drives in 50 degree weather here in Florida.
Possible symptoms are:
1. Thermostat is busted.
2. Fan temperature sensor is busted.
3. Low coolant in radiator.
Anything else it could be?
engine is turned off. I know that''s common on a warm day, but it''s been happening on short drives in 50 degree weather here in Florida.
Possible symptoms are:
1. Thermostat is busted.
2. Fan temperature sensor is busted.
3. Low coolant in radiator.
Anything else it could be?
11-16-2017, 09:57 AM
#2
Drifting
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Weird. I didn't even know there was a fan temperature sensor. It seems like that would be the culprit. The thermostat is going to stay open until the coolant cools off anyway, so I don't see that being the problem. And low coolant in the radiator would be easy enough to check. How about the coolant temp sensor? Do you see high temps when driving?
11-16-2017, 11:49 AM
#3
Long trips, yes I do. The needle gets to about 3-4 ticks below the hottest (or highest) mark. On a normal trip to work, which is about 11 minutes on the highway, it doesn't get that hot, especially now.
Last edited by gatrhumpy; 11-16-2017 at 11:52 AM.
11-16-2017, 11:51 AM
#5
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me thinks fan relay could be stuck in the on position
11-16-2017, 11:53 AM
#6
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Hmmmm. I'd say there's definitely something going on with your cooling system. You might try doing a full cooling system service. Flush, clean and refill. Of course, check the coolant level first to rule that out. Worst case scenario, the water pump could be going out. Or the thermostat.
11-16-2017, 11:55 AM
#7
Senior Moderator
I'm too lazy to look it up in the manual 
(well in reality, just got some actual work to do but find the proper relay, remove it while it's running to see if it goes out. It could very well be a sensor to but I'm thinking bottom up rather than top down. I.e. Fan running, what triggers fan to turn on from an electrical perspective: a relay. The sensor I would check next and then the water pump and coolant and all that jazz.
(well in reality, just got some actual work to do but find the proper relay, remove it while it's running to see if it goes out. It could very well be a sensor to but I'm thinking bottom up rather than top down. I.e. Fan running, what triggers fan to turn on from an electrical perspective: a relay. The sensor I would check next and then the water pump and coolant and all that jazz.
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11-16-2017, 12:39 PM
#8
Hmmmm. I'd say there's definitely something going on with your cooling system. You might try doing a full cooling system service. Flush, clean and refill. Of course, check the coolant level first to rule that out. Worst case scenario, the water pump could be going out. Or the thermostat.
11-16-2017, 01:10 PM
#11
Senior Moderator
Ahh in that case, that sounds like the relay is ruled out as well. Unless it's just intermittent 
of course if the fuse is pulled the fan will stop running!
of course if the fuse is pulled the fan will stop running!
11-17-2017, 07:39 AM
#14
I did check it in the radiator, and I could see remnants of coolant at the top, just below the radiator cap (when I take it off). In addition, the upper and lower radiator hoses are both hot, which tells me that the radiator is working that the thermostat is opening and allowing coolant to cycle through the radiator.
In an interesting observation that I had today was that when I was driving here around town for about 30 minutes in ~50 degree weather, I never heard the radiator fan come on when I was driving. However, as soon as I parked and turned the engine off at home, it came on. Weird.
In an interesting observation that I had today was that when I was driving here around town for about 30 minutes in ~50 degree weather, I never heard the radiator fan come on when I was driving. However, as soon as I parked and turned the engine off at home, it came on. Weird.
Last edited by gatrhumpy; 11-17-2017 at 07:41 AM.
11-27-2017, 07:13 PM
#18
Drifting
That's correct. The reason is because the tubes are closed up in the radiator so not enough circulation in the radiator to cool off the coolant. That's why the long run time of the fans.
When the car is running the water pump is moving faster so the radiator is more efficient to keep the engine cool. However, the fans are still running more that it should, you just haven't notice it yet.
In a perfect storm situation you car will get warm or even over heat. If not now but certainly in the near future.
You can confirm by removing the radiator cap when the car is cold and see if you can observe any coolant circulating in the radiator once the engine is hot. The engine is hot once the fan cycles on.
In a good radiator you will see coolant flowing from one side to the other when the thermostat opens and the flow stop when it closes.
When the car is running the water pump is moving faster so the radiator is more efficient to keep the engine cool. However, the fans are still running more that it should, you just haven't notice it yet.
In a perfect storm situation you car will get warm or even over heat. If not now but certainly in the near future.
You can confirm by removing the radiator cap when the car is cold and see if you can observe any coolant circulating in the radiator once the engine is hot. The engine is hot once the fan cycles on.
In a good radiator you will see coolant flowing from one side to the other when the thermostat opens and the flow stop when it closes.
11-27-2017, 08:58 PM
#19
That's correct. The reason is because the tubes are closed up in the radiator so not enough circulation in the radiator to cool off the coolant. That's why the long run time of the fans.
When the car is running the water pump is moving faster so the radiator is more efficient to keep the engine cool. However, the fans are still running more that it should, you just haven't notice it yet.
In a perfect storm situation you car will get warm or even over heat. If not now but certainly in the near future.
You can confirm by removing the radiator cap when the car is cold and see if you can observe any coolant circulating in the radiator once the engine is hot. The engine is hot once the fan cycles on.
In a good radiator you will see coolant flowing from one side to the other when the thermostat opens and the flow stop when it closes.
When the car is running the water pump is moving faster so the radiator is more efficient to keep the engine cool. However, the fans are still running more that it should, you just haven't notice it yet.
In a perfect storm situation you car will get warm or even over heat. If not now but certainly in the near future.
You can confirm by removing the radiator cap when the car is cold and see if you can observe any coolant circulating in the radiator once the engine is hot. The engine is hot once the fan cycles on.
In a good radiator you will see coolant flowing from one side to the other when the thermostat opens and the flow stop when it closes.
11-27-2017, 09:10 PM
#21
Drifting
Yes, but I see the temperature gauge go way past normal when the car is stopped at a long light, but the radiator fan does not come on when the car is on, even when we are stopped. I have felt the top and bottom radiator fan hoses, and they are both very warm, which tells me the radiator is working to get coolant to where it should.
Note, if you do nothing you will over heat and blow the head gasket or blow the water pump seal and the head gasket.
Faulty senders tend to be on or off not variable temps.
Last edited by 01acls; 11-27-2017 at 09:14 PM.
11-30-2017, 05:42 PM
#24
So I took my car in to have the overheating problem diagnosed. They said that there is a very small leak on top of the radiator, but I didn't notice because it wasn't leaking that much and the leak was drying up before it hit the ground. In addition, the coolant level was between the min and max. So here is what I've determined that could be the problem:
1.Radiator - I still have to buy a new radiator and replace it. But that is not causing the problem.
2.Low coolant level. The shop checked the level and it was fine, even with the small leak.
3.Radiator fan motor. The fan comes on when I turn the car off, and as I discovered while the car was ON, the radiator fan did turn on, but then turned off rather quickly after a run time of about 15 seconds when the car was on.
4.Radiator fan fuse. The fan runs, so the radiator fuse is fine. I visually checked it.
5.Fan relays. Once again, the relays allow the fan to come on, even when driving as I discovered today. I switched out the relays with another system and the relays were fine and the fan turned on. I tested the relays (4 prong and 5 prong) with a multimeter, and they were OK. The fan control relay is a normally open type A relay. I tested continuity between terminals 1 and 2 with the power disconnected and the relay out of the car. No continuity, which was fine. I have no idea how to test that there IS continuity between terminals 1 and 2 when power is connected to terminals 3 and 4. I also tested the Type S fan control Type B relay, which is 5 pronged, and that tested fine as well. I tested continuity across terminals 1 and 4 with power disconnected, and there was no continuity, which was good. Once again, I have no idea how to test the continuity with the power and relay connected. In the Haynes manual, it says on page 3-4 that "If the radiator fan motor is okay, but it isn't coming on when the engine gets hot, the fan relays might be defective." The radiator fan IS coming on, just not as often as I would like.
6. Thermostat. I have not ruled this out, but doesn't the thermostat fail in the open position, allowing the coolant to flow through the radiator?
7. Engine Coolant Temperature (ECT) sensors. The 2007-2008 has two sensors (2006 and earlier have only one ECT sensor). Sensor 1 is under the throttle body on the coolant passage casting, and sensor 2 is on the lower left side of the radiator. I suspect it could be the ECTs.
What are your thoughts?
1.
2.
3.
4.
5.
6. Thermostat. I have not ruled this out, but doesn't the thermostat fail in the open position, allowing the coolant to flow through the radiator?
7. Engine Coolant Temperature (ECT) sensors. The 2007-2008 has two sensors (2006 and earlier have only one ECT sensor). Sensor 1 is under the throttle body on the coolant passage casting, and sensor 2 is on the lower left side of the radiator. I suspect it could be the ECTs.
What are your thoughts?
11-30-2017, 08:44 PM
#26
Cruisin'
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I got a shop manual from Rockauto for my 2010 TSX it has more than I want for solving problems if you could find a "shop manual" for yours I think this may help?
Yes temperature sensors that regulate fans can go bad so replace any or all of them because you do not know the impedance values with temperature standard operating requirements.
You said they operate with relays this means ECU has a hold on the relays for shut time after engine is off, doubt program could be the problem?
Most all cars today run the same way so a schematic fan diagram would be helpful.
What year and type TL you own?
Yes temperature sensors that regulate fans can go bad so replace any or all of them because you do not know the impedance values with temperature standard operating requirements.
You said they operate with relays this means ECU has a hold on the relays for shut time after engine is off, doubt program could be the problem?
Most all cars today run the same way so a schematic fan diagram would be helpful.
What year and type TL you own?
11-30-2017, 09:58 PM
#29
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I found a relatived issue read through
https://acurazine.com/forums/1g-tl-p...ng-fan-764684/
His last words!
it was a bad temperature coolant sensor/switch.
https://acurazine.com/forums/1g-tl-p...ng-fan-764684/
His last words!
it was a bad temperature coolant sensor/switch.
12-04-2017, 09:24 AM
#31
Drifting
To check a relay apply power to the pins that have continuity and the open pins will then have continuity.
Defective Radiator... You're 10 ways wrong by not changing this first. A leak will allow air into the cooling system. ECT may not read correctly due to air in the system, ETC is reading the air pocket. Low coolant pressure lowers boiling point of coolant, car runs hotter than normal, ETC reading is not correct. Coolant will not siphon from over flow tank, air has least resistance so air enters coolant system. Coolant lost...etc.
12-04-2017, 09:18 PM
#32
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All we can do is try one step at a time while learning all the facets entailed with the cooling system
where sensors & relays are located and the ecu pinouts for this operation.
Radiators are $48 bucks on ebay.
We should know how many miles are on this tl.
where sensors & relays are located and the ecu pinouts for this operation.
Radiators are $48 bucks on ebay.
We should know how many miles are on this tl.
12-05-2017, 07:18 PM
#35
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Miles can gave a status of run time on all assaulted parts with a car having 200k or 400k will show a difference and how well one takes care of it.
You stated a small leak from rad so that should have been the first move to make, let us know what happens.
You stated a small leak from rad so that should have been the first move to make, let us know what happens.
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