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97 V6 radiator fan doesnt come on


supplybfk

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My wife's 97 V6 has a non operating fan. I gave power to the fan with a jumper wire and back probe from the battery, and the fan came on ( just to clarify, the radiator fan is the one closer to the passenger side right? ). Fuse and relay are good. I replaced the ECT about a year ago, and the upper radiator hose a few months ago. Have yet to check the fan module ( She works late and I have little of my own free time to work on her car ). No coolant leaks. Any help would be deeply appreciated thank you.

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Fuse and relay are good.

 

(1) Yes, the passangers side fan should be the radiator fan.

(2) You should first determine if the A/C fan runs (both fans should run with the A/C on). Therefore, turn the A/C on max and see if the A/C fan works. Diagnostics of your problem changes if both fans don't come on.

(3) You can (if you have not already) jumper between the No. 1 and No. 3 terminals of the fan relay and see if the radiator fan works. If so then you should be dealing with a bad relay.

(4) There is more then one fuse within the operating system both underhood and underdash. Fuses are between the the ignition and the radiator control unit and again between the radiator control unit and the fan relay, therefore, get a test light the probe both sides of ALL fuses, not just the one(s) you see marked as FAN etc., and replace all bad fuses if any are found and run the car to see if that does it.

 

Essentially, test all fuses, check to see if both fans don't work by running the A/C (if so post back because diagnostics take a different path), if only the radiator fans does not work manually jumper across the underhood panel to terminals 1 and 3 with the relay removed and see if the fan comes on, if so replace relay. Engine temperature must be hot enough to allow power to the relay for this to work.

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I agree with 'Turtlehead', and I have a generic fan diagnostic floating around too, though I can't remember if it had a circuit diagram with it. Just keep in mind that the V6 has not only two temp switches, but an oil temp switch the I4s don't have. All those switches along with the A/C circuit and ECU have the ability to tell the Radiator Fan Control Module behind the glove box to switch the fans on.

 

Let us know what you find.

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OK, so I turned on the A/C and both fans came on. I am a bit confused when you say jumper between 1 and 3 terminals. Do you want to apply a power or ground to one or is it just what you said and jumper wire to connect the two? Also I tested the relay via Haynes ( apply power to terminal B and ground to terminal D, and check for continuity between terminals A and C), however there wasn't any continuity between terminal A and C. I bought this relay new from Auto Zone a week ago. ( I know that even "new" parts can be bad ) All under hood fuses are good. You also wanted me to check under dash fuses as well?

Thanks for all the help.

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OK the fan came on. As I was checking the connection to the the sensors/switches, I unplugged the oil temp switch to check its continuity, then reconnected it. Then I moved on to the ECT switch and I unplugged it and re connected it. The fan came on. Now I don't know why it did that, but I am happy yet unsatisfied. Could anyone help me out on why the car did this?

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OK the fan came on. As I was checking the connection to the the sensors/switches, I unplugged the oil temp switch to check its continuity, then reconnected it. Then I moved on to the ECT switch and I unplugged it and re connected it. The fan came on. Now I don't know why it did that, but I am happy yet unsatisfied. Could anyone help me out on why the car did this?

Wow, now my problem seems to be intermittent. The fan seems to come on when I play with/unplug-replug either the ECT or the oil temp switch. When testing the oil temp switch, should there be continuity between the terminals when the engine is at normal op. temp?

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Lets see what James has to say about this since he has essentailly the same, the somewhat rare V6. As he states below there are 2 oil temp switches...

 

In the mean time try this: I assume you have power windows, do they work? If yes, then remove the power window relay from the underhood fuse panel. It should have the same part number as your original Honda relay, swap that with your cooling fan relay and see if that fixes it, if not then we can assume with good confidence that it is not the relay (quick and easy). After that it is beginning to sound like you do infact have a loose connection. The other possibility is that there is air trapped in the housing where the ECT's screw in.

 

You should have two ECT switches, one in the housing against the block on the upper radiator hose and one in the housing at the thermostat (lower radiator hose). You can disconnect the connector at the one that you think is causing the problem and jupmer the wires at the connector which will cause the car to think that the ECT switch is closed. With the car hot and everything else working the fan should come on. If it does and you can repeatedly get the car to do it then the ECT you replaced earlier may be bad. Did you use a Honda ECT switch? They are switches and like any switch they can sometimes get stuck or stickey (stickey would cause intermittent problems), so in theory, if it is stuck open while the car is hot it is not telling the computer to engage the remainder of the cooling system and thus no fan...

 

As far as testing fuses, YES, when diagnosing an electrical problem check every fuse in the car first and replace any that are blown. Often times the electrical circuits run through multiple fuses, even though when you read the fuse panel cover you would be lead to believe that it is only the one that is shown. It only takes a few minutes with a test light to do it and is often times the first place to start. But as far as your issue goes and what you have done thus far I am thinking it is not fuse related.

 

You have learned one thing though, by running the A/C and both fans coming on you can atleast drive the car and minimize the potential of overheating. You can also run the heat on high, even on a hot day with the windows down which will help pull heat out of the cooling system...

 

 

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