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any suggested fixes for this problem? Yeah , view a wiring diagram to see what all is involved in turning on the cooling fans an test with a DVOM - digital volt ohmmeter . Free wiring diagrams here http://www.bbbind.com/free-tsb/ Enter vehicle info. year make ,model an engine . Under system click on engine , then under subsystem click on cooling fans. Click the search button then the blue link . Looking at the diagram i see three relay's - fan control , high fan control , lo fan control . All three relay's are commanded on by ther PCM - engine computer . Checking for DTC'S - diagnostic trouble code's with a scan tool . Double check your work - pinched wiring etc...... check for high speed fan relay stuck contacts .
A significant number of cars have an electric cooling fan supplied by a battery live rather than an ignition live because it is believed the cooling fan should be able to start or to continue running after the engine has been switched off.
Coolant will continue to circulate after switch-off due to thermo-syphon activity and it could reduce mechanical stress on engine components to continue cooling.
Some people modify the cooling system by fitting an additional manual switch to over-ride the thermal switch for use when standing in traffic, for whenever continuous operation is desired or to use in emergency should the thermal switch operation fail.
In the absence of such a modification that has been inadvertently switched on the fault will be due to a faulty thermal switch, a faulty or stuck relay or shorted wiring. Disconnecting the thermal switch should stop the fan and if it does it indicates the switch is faulty. The switch is mostly fitted into the radiator header tank but sometimes is fitted to the bottom tank or the thermostat housing.
turning of the ac switch will indicate if it is an ac problem for the fans.
some cars have the radiator fans running for up to 10 minutes after shut down . Run the fault codes to see if there is a faulty temperature sensor. how it works is this
the sensor is connected to the ecm and has power passing through. it When the sensor sensor a preset coolant temperature the power to the ECM is altered and so the ECM energizes the relays for the fans. If the fans are running continuously after shut down then the ECM still has the relays energized as it is still reading the requirement from the sensor.
Your cooling system works by getting air flow over the radiator and good circulation of coolant in the radiator as well as other areas of the motor.
The fan for your radiaror is electric, but it is designed to run at different speeds depending on conditions. First, I would verify that the fan DOES run. Sitting in the driveway with the engine at operating temperature, turn the A/C on and see if the fan speed increases right away or increases after running for 10 minutes. It should have a higher pitched sound. Look at the temperature gauge again and see if it is still at operating temperature. If the temperature continues to climb, turn the heater on full blast and watch the temperature gauge, it should drop.
No increase in fan speed means you could have a module problem or other problem related to the fan speed. In your relay box, relay "K11" is the fan relay. The relay box is in the engine compartment. The underside of the cover will identify what relays go for what. Some Jeeps used 2 relays, 1 for low speeds and the other for high fan speeds.The fan and module are replaced as a unit. The PCM (power control module is the brain for the engine management system including the controling of the fan relays. Sometimes the relays are the same and you can swap them with each other to see if there is a change. Note: If the temperature is normal when you are driving down the road, than the cooling system is normal and it is the fan.
Good luck.
From what you have described, which is a rapid over heating of the radiator coolant fluid and therefore a hot engine condition, it would appear that the thermostat in the engine's cooling system is faulty.
If the thermostat is sticking in the closed or nearly closed position temporarily, there will be no flow or very little coolant flow between the engine and the radiator and the engine will overheat.
You have advised that after the engine is shut off , and radiator coolant fluid has cooled, you re-start the engine and drive the car without the overheating condition occurring again and the radiator coolant temperature is normal. This time there is no overheating because the thermostat is working normally.
You should have the thermostat replaced as soon as possible because allowing the engine to overheat can cause very expensive engine damage.
If you had a continuing overheating condition then I would suspect both the thermostat and the water pump. However as the overheating seems to be only temporary, and clears itself after you have shut down the engine and re-started it 10 minutes later (without further overheating arising) then I think you only have a faulty thermostat.
Please also check that the electric fans which draw air through the radiator are operating. These run on a temperature sensor and will switch on automatically once the radiator coolant fluid reaches a certain temperature and then switch off again when the fluid temperature reduces. You will hear them running once they start up. If these fans are not working the radiator coolant can quickly overheat in various driving and temperature conditions because there will be insufficient air flow through the radiator to cool the fluid. If the temperature sensor is faulty or has died, or if the electric motors running the fans are faulty, the fans will not operate.
You can check if the fans are working by turning on you Air conditioning. They should run constantly with the A/C on. Also bear in mind that the fans do not normally come on until the coolant temperature hits around 225-228 degrees.
from memory the electric fan runs constant when air conditioning is turned on i would suggest the thermal control for the electric fan monted to the radiator is not functioning correctly is normally mounted to a flat spot on radiator
This is because of the improper circulation of the coolant, if the AC turned on then the engine load will be considerably increase and spoil the thermal switch (which initiate the cooling fan to run). So you better clean the radiator and check the radiator pump, then replace the thermal switch to get the things done.
The air conditioner compressor is driven via belt by the engine; if the engine is off, the compressor is off = no AC.
You didn't mention which fan is still running but I'll assume it is the one underthe hood, not the one that circulates passenger compartment air.
What is running is the electric fan that assists with cooling of the heat exchanger of the AC system.
You probably have a thermal switch or relay that is not releasing.
Locate the relay/fuse box and check if there is a chart of the relays and fuses to locate the one that isn't releasing and try swapping two relays with the same part number on them to check relay function.
ok there is a relay in the power dist. box for the a/c fan it has a high and low side or there may be two diff. relays what I usauly do is swap this one or them for known good ones check part numbers swap from i.e fuel pump power window and such if that doesnt work you most likely have the winding in the fan motor itself fused together basically worn out to check this use a ohm meter check across the pins in the fan side of the plug with it unpluged only two at a time should have flow black wire is ground leave and usually in the center check the other two without take the negative of the meter off the ground both should have continuity now check the other ones negative to one hot and positive to the other hot if these have continuity you have a shorted fan motor it needs replaced.. let me know if this works or if you need clarification thanks Danny
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