2002 Overheating mystery

[PJTBRD]

I have a problem with the cooling fan continuing to run after shutting down the engine. To the point of running the battery down. Could coolant be the problem or thermostat?

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[tbird.blue]

Hi, check there is coolant in thermostat housing. I have had the expansion tank show as correct level and yet coolant had been leaking out of the dual valve fitting and not getting sucked back from expansion tank, causing engine to eventually over heat and keep fan on. Also check all the connections for the fan by pulling apart and connecting a few times, in case there is a bad connection. I also had this with the fan turning off and on repeatedly, even when engine was cold?
Good luck

 

[uncle barry]

I have a problem with the cooling fan continuing to run after shutting down the engine. To the point of running the battery down. Could coolant be the problem or thermostat?

Have you checked your relays? And for a couple of bucks (Rock Auto) get a new thermostat. I owned a '67 XKE. Drove it cross country a couple of times. I an overheating problem in Phoenix. Just pulled into a shop and learned that in severe heat I needed to remove thermostat
and REPLACE with a Restrictor. No more problems. BUT when weather cools, thermostat must be replaced.

 

[highwayghost]

I have a problem with the cooling fan continuing to run after shutting down the engine. To the point of running the battery down. Could coolant be the problem or thermostat?

I thought the 2002 had a hydraulic cooling fan system??

 

[Gus Gutz]

Have you checked your relays? And for a couple of bucks (Rock Auto) get a new thermostat. I owned a '67 XKE. Drove it cross country a couple of times. I an overheating problem in Phoenix. Just pulled into a shop and learned that in severe heat I needed to remove thermostat
and REPLACE with a Restrictor. No more problems. BUT when weather cools, thermostat must be replaced.

I'm thinking you have something else going on. It's been over 100 degrees for the last two weeks here in SoCal and I don't have to take the thermostat out to keep my car cool..

 

[The Flash]

Bad things happen to old cars. I have to maintain my 2003 all the time it's a daily driver but wife only drives 6 miles a day most days. makes for more problems. Has 67.000 miles, lucky I can fix it all the time. A/C has been a problem this year, replaced most of the components.

 

[Txgal]

My 2003 Thunderbird was having overheating issues. We replaced the radiator, the coolant tank and now the fan is running really loud. Could it be the fan clutch? I am getting really frustrated. Anyone else had problems?

 

[doug7740]

The PCM monitors certain parameters such as engine coolant temperature, vehicle speed, A/C on/off status, and A/C pressure to determine engine cooling fan needs. The PCM controls the fan speed and operation using a duty cycle output on the Fan Control Variable circuit. The fan controller, located at or integral to the engine cooling fan assembly, receives the FCV command and operates the cooling fan at the speed requested by varying the power applied to the fan motor.

The reason your fan is running loud is because it is continuously running at high speed. The cylinder head temperature sensor provides a signal to the temperature gauge and will invoke fail-safe cooling. I would start by checking for faults in the PCM. Even if there are no faults stored, clear the PCM memory with the scan tool so you’re sure that the system isn’t in fail-safe cooling.

If the fan is still continuously running at high speed, there is a possibility that either the cylinder head temperature sensor or the A/C pressure transducer sensor is defective. These can be easily verified by looking at the data stream on the scan tool. If both sensors are operating as designed, that would indicate that the microprocessor in the cooling fan motor is defective, and the cooling fan motor will have to be replaced.

doug7740
1955 Thunderbird Blue

 

[Txgal]

Thanks for the reply. Question: IF the sensors are bad do I need to replace them or if I just replace the fan will that fix the problem?

 

[doug7740]

Don’t start replacing parts without doing some testing first. The easiest way to test the sensors is by looking at the scan data. Since the engine overheated did it damage the cylinder head temperature sensor? By using the scan data, you can compare the cylinder head temperature sensor reading with the ambient air temperature sensor reading. On a cold engine they should be within a few degrees of each other. Same thing goes for the A/C pressure transducer sensor. Does the scan data show high A/C pressure without operating the air conditioner? Depending on what you find will dictate if further testing is needed. Since the engine overheated, is the system is in fail-safe cooling mode? If there no faults stored in the PCM or the Dual Automatic Climate Control module, by clearing the memory in these control modules will reset the control module and possibly correct the problem.

Don't start by throwing parts at the car hoping that it will fix the problem. I always use the scan tool first and then move on to pinpoint testing before I replace any parts.

doug7740
1955 Thunderbird Blue