What can cause both radiator fans to not come on?


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2006-05-25 10:40:28
2006-05-25 10:40:28

I have a 1988 oldsmoble cutless cirra wih same problem I have replaced the colant fan switch and the coolant fan relay but to no avail have not solved this problem however the fan on the back side of the radiator does come on when I turn the key off but the fan on the front side of the radiator never comes on any help yet??? You might need a diode wire. *You may have a blockage in the coolent system which can prevent the flow of the hot coolent to the radiator fan switch. Check the temprature of the upper and lower radiator hoses carefully by touch. If the one of the hoses is cool while the other is hot there may be a blockage.


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you may have an overcooling problem. check your thermostat and temperature switch. the thermostat regulates fluid in and out of the radiator, and the switch tells the fans to come on to cool the engine.

The fans normally come on when needed. Is the car running hot -- is the temperature gauge reading above normal? If so, there's a problem with the fans or the cooling system. If not, don't worry about it.

Blown fuse, Heat sensor broken or disconnected, thermostat jammed

Check the thermal relay for the cooling fans.

No. One fan is for the radiator, and the other is for the condenser. If you have the A/C on, they should both be on. Else, just the one for the radiator, if the thermostat is open.

First remove both of the radiator's upper and lower hoses, then remove the two bolts that hold the brackets that hold the radiator in place. Unplug both fans electrical harnesses and the small hose that connects to the radiator overflow reservoir. Now you should be able to pull the entire radiator out of the car including both fans that are held to the radiator by four bolts each.

Unscrew the bolts that connect the fans 2 the radiator then unplug the plugs and it should come out..

Low coolant, stuck thermostat, failed waterpump, plugged radiator, inoperative radiator fans, etc.

The fans are controlled by a temperature switch, which normally turns the fans on when the engine temp reaches about 212 to 220 degrees.

fan2 should come on when the a/c is on. so both fans should be running when the a/c is on. when the a/c is not on, the driver side fan should come on when engine temperature gets up to 210 degrees. What would cause fan 1 to not come when a/c is running

The Radiator fan relay has probably failed. It is bolted to the lower side support next to the radiator.

There is a technical service bulletin that Dodge has put out addressing that problem. It is due to the relay and a modification that are required.

Whenever the AC is turned on, both cooling fans also come on. Otherwise, during normal operation only one fan comes on when activated to maintain correct engine temp.

What do you mean by ``switch``? Coolant temp sensor could be bad, Fan relay could be bad, or fans could be bad. Is radiator completely full? An air pocket could cause problems. By switch I mean the temp sensor located on the radiator itself. I have put direct voltage to the fans and they operate. The radiator is new and full of antifreeze. On this particular model there are two boxes with relays and fuses under the hood on the driver's side. Box that is closest to the headlight has one relay listed as fan no1 and the other box has relays listed as fan no2 and fan no3. Which one of these operates the radiator cooling fans? Is there a way to test these relays? Does engine have another sensor near thermostat housing? This is normally the one that controls the fans. Either way, if sensor has one wire to it , disconnect it and ground it to engine with ignition on. fans should run. If not, it is probably a relay. If you have air conditioning, the fans will both run when you turn on the air conditioner with the engine running. (At least the 1998 Camry is this way). Both fans run to keep airflow over the condenser coils. If both fans run this way, then wiring, relays, etc. can be assumed to be alright. Then more than likely, your problem is the radiator temperature switch (you will see wires going to a device that is screwed into the radiator near the bottom, by the lower radiator hose) This switch should turn on the fan when the radiator fluid gets hot. I am not sure this fan will run when the car is turned off but at least you know the wiring and the fans themselves are operational.

Yes, when the a/c is used the engine works harder which rises the temp of the engine then turn the fans on to cool the radiator.

Electric fans on vehicles only run when necessary,,,over heating or the temperature getting near a dangerous level. They just do not come one when the vehicle runs. Normally they WILL come on if you turn the AC on because of the added stress on the engine.

The system has to be sealed in order to work properly. You have a leak somewhere, could be as simple as a faulty radiator cap. Have the system pressure tested and your leak will show up.

More than likely the radiator fan resistor has gone bad. It is located at the bottom corner of the radiator.

The rad fan relay has failed. It is loacted on the driver side of the radiator, under the air filter box, on the frame rail.

It could be one of many things.......radiator fans notworking/low on coolant/stuck thermostat/ radiator may need to be flushed......

hey there thanks for any help, just bought a nissan primera 1990, both radiator fans dont work and im told the sensor may need changing, does anyone know where i can locate it to replace?

The engine temperature must reach 232-235 degrees in order for the cooling fans to come on. They will shut off at about 195-200 degrees. Also when the air conditioner is on the cooling fans automatically come on regardless of temperature.

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