Why do both radiator fans run on high any time the engine is running,...hot or cold

A hot running engine is usually caused by a cooling system problem. Make sure the coolant level is full and the thermostat.. rad fan.. radiator cap and water pump are all functioning correctly. Make sure there are no restrictions in front of the radiator to obstruct air flow and coolant circulates properly throughout the radiator. As for losing oil, check for the obvious..... Leaks. If no major leaks and you have a high mileage engine, suspect the oil to be burning within the engine. A constantly hot running engine can also cause the oil to break down quicker resulting in consumption, especially if oil changes are neglected

With the thermostat out you should see a lot of circulation. If not investigate water pump. Is the fan electric fan working? Bypass the relay and run the fan whenever the engine is running. If it doesn't overheat with the fan running then investigate fan control. make sure the coolant is topped off and use a thermometer in the radiator to verify temperature.

Hi Kevin. Since your fan run even when the engine is cold,my advise is to go direct to the temperature sensor,which actually is the main culprit for causing the confusion to the ECU. Since the temperature sensor does not work correct,the message send to the ECU is wrong - like is sending that the engine is hot - the ECU order the fan to start. Also there is another possibility for the fan relay to remain stuck and leave the fan to work constantly.

Good Luck.

What is this cap on?? Radiator or windshield washer reservoir? Something else?

If the radiator, most newer cars have a plastic bottle or tank that has a "cold" and "hot" level indicated. You should be able to see the coolant level thru the tank. You should NOT need to open the radiator cap if your car has this tank. Add a 50/50 mixture of water and coolant (of a type your car requires) up to the "cold" mark and start the car. Let it run with the heater set to HOT and fan set to HIGH. Continue adding the 50/50 mixture to maintain the coolant level to the HOT level mark on the tank as needed with the engine running. Stop when there is HOT air blowing out of the heater.

If your car does NOT have this tank, you may only open the radiator directly when the engine is COLD. Wait several hours for the engine to cool after shutting off before attempting to remove the cap.

When cold, press DOWN on the cap WHILE turning. Most caps will come off after a 1/4 to a 1/2 turn. Start the engine and set heater HOT and fan to HIGH. Continue to add a 50/50 mixture of coolant to the radiator until the heater blows HOT air. The coolant level in the radiator should be just under (1" or less) from the bottom of the radiator opening.

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First thing to check when the engine is cold is that if there is enough antifreeze in the radiator and after you run the engine for about 5/10 minuter check both the rad hoses to see if they are both at the same temperature, if the return hose which is the bottom one is cold then replace the thermostat. If both hoses are hot or same temp then make sure the radiator fan comes on?

change the thermostat, sounds like it could stuck open and wont allow the engine reach operating temp, also test the constant control relay module located to the right of the battery as your facing the front of the car, also test coolant temp switch it might be defective and producing a high voltage that would cause the fans to constantly operate no matter the temp. Hope this helps

Assuming the check engine light is not on, I would want to know what the engine temp sensor is doing.
A scanner would tell you what the temp sensor is showing - if it is unplugged or there is a problem with the wiring the fans will run as a default to prevent the engine from overheating. It could be a fan relay but I doubt it. A relay usually works or not.

Your radiator is clogged, there is not enough flow thru the radiator to keep the engine cool. A radiator shop should be able to flush and clean it, just beware that when radiators get clogged for a long time and there cleaned, they tend to leak.

Since you have replaced the relay and fan switches, does the fan come on with high engine temperature? If not, this fan must run with engine temperature or the engine will overheat. If so then check the radiator for clogs, and the thermostat. Start the engine and run until normal temperature, feel the radiator carefully by hand, it should be hot at the top and generally get cooler as you feel toward the bottom, without any cold spots. If you find a cold spot then the radiator is plugged and needs to be cleaned or replaced. The thermostat is located at the left end of the cylinder head, underneath the ignition module on the 1.9L, it could be stuck closed, a good method of checking this it to feel the upper radiator hose while the engine is warming up, it should become very hot as the engine runs, so be careful not to burn your hands. If it stays cold until the engine is overheated then it is stuck closed. Also check the exhaust pipe, with antifreeze in the cooling system there should be no white smoke coming out while engine is running, if there is the cylinder head gasket may be blown, this will require more intense repair and should be taken to a shop. Hope this helps, let me know.

Run the engine and look at the header tank , is there lots of air bubbles coming back out of the water if is then the head gasket may have split and that is down to either a can of Radweld or a strip down repair

If the radiator is not uniformly hot them I would go for that as your problem

Normal operation is that the engine starts the thermostat is closed , engine block heats up and opens water starts to circulate around the block

So to check that you need to fill the radiator with cold water run it for a few minutes check the bottom hose it should be cold

The stat opens and the bottom hose should get hot as the water from the block is pumped into the radiator for cooling.

The radiator should get hot all over and the cooling fan should kick in when the sensor hits the over limit stop.

If that does not happen then get someone to remove the stat altogether (It is only there to get the engine block warm quickly in cold regions )

In which case the bottom hose should go from cold to warm to hot