A/c fan not wotking if i un plug the wires from the radeitor and connect them directly with a wire the a/c fans goes next to the redator but not from inside the car checked all fuses everything seems to be ok xpect the fan my car is 1997 bmw 316
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Re: a/c fan not working
Are you saying the fan never comes on or just doesn't come on when you're watching it? most fans come on when the radiator coolant reaches a certain temp, then flips a relay to send power to the fan.
if the car is warmed up and the fan is not coming on (or if the A/C is selected on and fan doesn't come on), i would suspect the relay since you already proved separate power to the fan does make it work.
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First make sure it is really hot by sprinkling some small amount of water on the block- If it sizzles-your gauges are not lying.
Next, are the fan/fans running? That will be either the radiator temp sensor, low coolant,bad fan or bad fan wiring. First- direct wire the fans to the battery. If their good, connect the wires at the sensor together (you may have to turn on the ig). If they don't run the fan, see if the hot lead to the rad sensor really is hot. See if the ground wire from the fans is good. Follow back any faults to the main fuse block and beyond.
Next would be the thermostat. Is the place top hose is connected to. Put thermostat in some hot water and watch it open. Next in the freezer and watch it close.
Check your oil for water/coolant in quantities undesirable. If there is water in there, you have some bigger problems.
Last- though maybe should be first- is there a cat spread eagle cross your radiator - or a piece of plastic sack or something. Are the AC fins clean can you take a garden hose a spray water thru thu whole mess, what about the inside of the radiator" ? Any pensoil white scum or growth?
That will give you some direction. Hope it's one of the cheap problems
Follow the wiring back from the fan motor, the relay is often found at about the height of the bottom of the radiator on the inner fender. Check that connection is clean and free of corrosion. Check that the fan works by taking two trailing wires directly from the bettery terminals and connecting then to the fan motor directly. Use a voltmeter and check the voltage at the relay when engine is cold and shortly after the radiator top hose from the engine becomes hot (the coolant sensor should have signalled for the fan to switch on at this time). No voltage indicates a break in the circuit or faulty sensor. Voltage but no fan indicates faulty relay
you could apply 12v battery power directly to the fan itself...there should be 2 wires coming from the center of the fan, follow these and you should come to a plug that you can un hook as if to remove the fan. on the fan side of the wires, hook them to 12v power, one wire + one to - if the fan does not turn, switch the wires polarity and test again. ( the fan should run either way, polarity just dictates direction of rotation) if the fan spins, the problem is on the car side. if not the fan itself is suspect. test vehicle side with known good fan or test light.
First look to see if you have a fuse for the blower motor...then you will want to disconnect power to the fan an jump 12 volts to the fan motor to see if it works...if ok, then there is a speed control resistor that sometimes goes bad located on the heater assembly...It is usually right past the fan so the fan can keep it cool and has 4 or more wires on it. if all else ok then last would be the switch inside car
Do the fans come on when the engine overheats? If so nothing wrong with the circuit and the thermostat(not thermo switch!) or radiator is to blame. Test the fan. There are 2(if you have A/C fitted) Disconnect the electrical plug from the fan. Run 2 wires from the battery straight to the fan and see if the fan comes on. (Be careful when connecting not to short circuit the wires. Theres a lot of power in the battery!) Polarity does not matter. This is a direct current motor so reverse polarity will only make the fan turn in the wrong direction. If the fan turns reconnect its electrical connection and move to the next step. To test the fan circuit locate the thermo switch. It is on the bottom right of the radiator and has 2 wires connected. disconnect the electrical plug and short circuit the 2 wires by inserting a piece of wire into the connector with the ignition on. The fan should come on. If it does the thermo switch is at fault and needs replacing. With the electrical sorted there is not much else. Like I mentioned it is either the radiator(blocked) or the thermostat(sticking) Radiator can be taken to a service centre and have them clean it out for you. The thermostat cannot be repaired and needs to be replaced. It can be removed and the engine will still operate, but just take longer to warm up. I'm not sure on the '99 model, but it is usually located on the right hand side of the engine at the bottom on the water pump housing.
First of all, you have to check the status of the fan. Wire it directly to the battery and if it comes on than the problem is with a bad connection or the temperature sending unit. This controls when the fan comes on and goes off
check your fan motors unplug the wires in the back of the motor take 2 wires from the battery one positive one negitive to the plug on the actual motor connect the power direct you cant di it wrong it will only go backwards so your taking the power from the battery directly to the fans see if they work.remember 2 wires 1 from the positive to the fan plug connect to 1 prong. other from the negitive to the other prong fans will kick on if there good.if there good plug back in as b 4,make sure your temp gauge is working,fuses,relays
The engine fan is a 12 volt DC motor in a housing attached to the radiator. Unplug the fan and run two wires from the battery to the fan plug connections, if it runs the fan is good and you need to look next to the temperature sensor which tells the fan to turn on due to engine heat. If fan does not turn on with direct electricial connection then you can buy a replacement at advance, autozone, or on ebay motors. Note apply power to the fan's connector, not to the car wiring harness. If your fan is good I believe the there are two termperature sensors screwed into the driver's side of the engine head. They look similar but have different electrical connectors.
Direct wiring of the fan is not a good idea. The fan will not cycle and it could burn the fan up. It would be best to get another harness from the auto parts store or from a salvage yard. The auto parts store should have a diagram to wire in the harness or you can see how the harness wires in by looking at another vehicle. If you are going to direct wire the system, be sure to put in an inline fuse on the hot wire.