Cooling fan running all the time...
11-04-2008, 03:22 AM
#1
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Cooling fan running all the time...
Is this a common issue? I think it thinks its hot, so in the cold weather it starts hard and stumbles at first and the fan never shuts off. I logged a while ago and it said something about a electrically controlled thermostat? Is that the one on the back of the head, or the one on the side of the block?
TIA..
TIA..
11-04-2008, 08:00 AM
#3
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I've read your issue traced to both bad sensors, as well as water in the ECU compartment.
If it's a bad sensor, it probably set a code (may or may not illuminate the CEL, mine did not).
11-05-2008, 05:12 AM
#4
If the fan runs with the A/C OFF, but only when the engine is running, ....
one of the two coolant temp sensors is faulty. The sensor at the back of the cylinder head, sends coolant temp info to the ECU to control the various temp related engine parameters like fueling, ignition timing and boost pressure. The coolant temp sensor in the lower radiator coolant return hose, sends temp info to the ECU regarding how much heat is being dumped from the coolant passing through the radiator. When the return coolant temp exceeds a certain value, the ECU runs the radiator cooling fan, first on low speed, then on high speed if low speed doesn't cool enough. The electrically heated t-stat, is powered by the ECU, by a PWM variable voltage, in order to open and close the t-stat as needed to control bulk coolant temperature based on engine load and rev/min. If the heater element built into the t-stat wax motor capsule fails, the t-stat will control coolant temps like any regular t-stat does, in a coolant temp dependent, reactive mode. Normal heated t-stat operation provides for load and speed referenced, proactive coolant temperature control.
The cooling fan on the drivers side, is the main, ECU controlled engine cooling fan. The fan on the right, or passenger side, is the Auxiliary fan, and is controlled by the A/C controller, used to cool the A/C condenser.
If the fan/s runs with the key off, intermittently, even with a cold engine, then it's likely the ECU box has a lot of water inside, from a leak from a cracked cover, or a cover that is not installed correctly. Water in the ECU box will short out the components inside, and is a known cause for the fan running with the key OFF, usually until the battery is dead.
The cooling fan on the drivers side, is the main, ECU controlled engine cooling fan. The fan on the right, or passenger side, is the Auxiliary fan, and is controlled by the A/C controller, used to cool the A/C condenser.
If the fan/s runs with the key off, intermittently, even with a cold engine, then it's likely the ECU box has a lot of water inside, from a leak from a cracked cover, or a cover that is not installed correctly. Water in the ECU box will short out the components inside, and is a known cause for the fan running with the key OFF, usually until the battery is dead.
03-14-2017, 10:49 PM
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I THINK I have a similar issue and wanted to see if I am right.
When I turn on the car I hear the fan. when i bought it the guy delivered it with low coolant level ( am not sure how low it was but the red coolant light was on. I immediately went to buy coolant and topped it off and the dash warning went away. However the fans seem to me like they're always running.
Example: When I accelerate from parked status, I can hear what sounds like when the car is running on a hot day and the fans are on max, however the sound only sounds like its going up matching my revving (i have not tried driving it with the windows down yet but i might give it a shot.
Could this also be the temperature sensors that was mentioned above? or is this something normal I should expect. with my BMW I was used to hearing my fans often because I lived in the devils armpit aka San Antonio TX, where summer is a chilly 110 F. but it's only ... 67 degrees outside at best in Orlando right now. Any pointers to point me in the right direction to try some DIY stuff before i hire a mechanic to do a diagnostics would be appreciated. (in between jobs with low funds can't afford to blow money on random things)
i appreciate any ideas you can give me.
When I turn on the car I hear the fan. when i bought it the guy delivered it with low coolant level ( am not sure how low it was but the red coolant light was on. I immediately went to buy coolant and topped it off and the dash warning went away. However the fans seem to me like they're always running.
Example: When I accelerate from parked status, I can hear what sounds like when the car is running on a hot day and the fans are on max, however the sound only sounds like its going up matching my revving (i have not tried driving it with the windows down yet but i might give it a shot.
Could this also be the temperature sensors that was mentioned above? or is this something normal I should expect. with my BMW I was used to hearing my fans often because I lived in the devils armpit aka San Antonio TX, where summer is a chilly 110 F. but it's only ... 67 degrees outside at best in Orlando right now. Any pointers to point me in the right direction to try some DIY stuff before i hire a mechanic to do a diagnostics would be appreciated. (in between jobs with low funds can't afford to blow money on random things)
i appreciate any ideas you can give me.
03-15-2017, 03:37 PM
#6
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The first thing you need to do is to check to see what DTC's (Diagnostic Trouble Codes) are present. If you don't have any way to check codes you can go to your local Autozone and have them read the codes for you.
Any time the ECU throws a code for a malfunction in the cooling system the default is to run the fans on high all the time. Once you reset the codes the fans will operate normally. If the condition that caused the DTC reoccurs the fans will again run all the time.
A better alternative is to be able to read and reset codes yourself. If you have an Android phone go to Google Play and download TorquePro for $4.95. Clicky click® Then go to Amazon and pick up a ELM327 OBDII bluetooth transmitter to be able to communicate with the TorquePro app for around $10.
Post up your codes and we can figure out the next step. It could be as simple as replacing an $8 sensor. Clicky click®
Any time the ECU throws a code for a malfunction in the cooling system the default is to run the fans on high all the time. Once you reset the codes the fans will operate normally. If the condition that caused the DTC reoccurs the fans will again run all the time.
A better alternative is to be able to read and reset codes yourself. If you have an Android phone go to Google Play and download TorquePro for $4.95. Clicky click® Then go to Amazon and pick up a ELM327 OBDII bluetooth transmitter to be able to communicate with the TorquePro app for around $10.
Post up your codes and we can figure out the next step. It could be as simple as replacing an $8 sensor. Clicky click®
06-12-2018, 02:24 PM
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one of the two coolant temp sensors is faulty. The sensor at the back of the cylinder head, sends coolant temp info to the ECU to control the various temp related engine parameters like fueling, ignition timing and boost pressure. The coolant temp sensor in the lower radiator coolant return hose, sends temp info to the ECU regarding how much heat is being dumped from the coolant passing through the radiator. When the return coolant temp exceeds a certain value, the ECU runs the radiator cooling fan, first on low speed, then on high speed if low speed doesn't cool enough. The electrically heated t-stat, is powered by the ECU, by a PWM variable voltage, in order to open and close the t-stat as needed to control bulk coolant temperature based on engine load and rev/min. If the heater element built into the t-stat wax motor capsule fails, the t-stat will control coolant temps like any regular t-stat does, in a coolant temp dependent, reactive mode. Normal heated t-stat operation provides for load and speed referenced, proactive coolant temperature control.
The cooling fan on the drivers side, is the main, ECU controlled engine cooling fan. The fan on the right, or passenger side, is the Auxiliary fan, and is controlled by the A/C controller, used to cool the A/C condenser.
If the fan/s runs with the key off, intermittently, even with a cold engine, then it's likely the ECU box has a lot of water inside, from a leak from a cracked cover, or a cover that is not installed correctly. Water in the ECU box will short out the components inside, and is a known cause for the fan running with the key OFF, usually until the battery is dead.
The cooling fan on the drivers side, is the main, ECU controlled engine cooling fan. The fan on the right, or passenger side, is the Auxiliary fan, and is controlled by the A/C controller, used to cool the A/C condenser.
If the fan/s runs with the key off, intermittently, even with a cold engine, then it's likely the ECU box has a lot of water inside, from a leak from a cracked cover, or a cover that is not installed correctly. Water in the ECU box will short out the components inside, and is a known cause for the fan running with the key OFF, usually until the battery is dead.
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06-12-2018, 02:26 PM
#8
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one of the two coolant temp sensors is faulty. The sensor at the back of the cylinder head, sends coolant temp info to the ECU to control the various temp related engine parameters like fueling, ignition timing and boost pressure. The coolant temp sensor in the lower radiator coolant return hose, sends temp info to the ECU regarding how much heat is being dumped from the coolant passing through the radiator. When the return coolant temp exceeds a certain value, the ECU runs the radiator cooling fan, first on low speed, then on high speed if low speed doesn't cool enough. The electrically heated t-stat, is powered by the ECU, by a PWM variable voltage, in order to open and close the t-stat as needed to control bulk coolant temperature based on engine load and rev/min. If the heater element built into the t-stat wax motor capsule fails, the t-stat will control coolant temps like any regular t-stat does, in a coolant temp dependent, reactive mode. Normal heated t-stat operation provides for load and speed referenced, proactive coolant temperature control.
The cooling fan on the drivers side, is the main, ECU controlled engine cooling fan. The fan on the right, or passenger side, is the Auxiliary fan, and is controlled by the A/C controller, used to cool the A/C condenser.
If the fan/s runs with the key off, intermittently, even with a cold engine, then it's likely the ECU box has a lot of water inside, from a leak from a cracked cover, or a cover that is not installed correctly. Water in the ECU box will short out the components inside, and is a known cause for the fan running with the key OFF, usually until the battery is dead.
The cooling fan on the drivers side, is the main, ECU controlled engine cooling fan. The fan on the right, or passenger side, is the Auxiliary fan, and is controlled by the A/C controller, used to cool the A/C condenser.
If the fan/s runs with the key off, intermittently, even with a cold engine, then it's likely the ECU box has a lot of water inside, from a leak from a cracked cover, or a cover that is not installed correctly. Water in the ECU box will short out the components inside, and is a known cause for the fan running with the key OFF, usually until the battery is dead.
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