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96 Legacy Cooling Fan Wiring Problem


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Hi,

On my 96 Legacy Outback, I have been having problems with the two cooling fans on the radiator. I've had the car about a year now. Besides the head gaskets needing to be changed (car only had about 130,000 miles on it), I had to change a relay for the cooling fan because the MIL was on with the code for the cooling fans (sorry I don't remember which code). I went through and tested the 4 relays, and only 1 of them appeared to not be working. I replaced it and the MIL went away. During the fall/winter, the MIL came back on with the same code. From googling a list of OBD codes for Subaru, I think the code was P0483 Cooling Fan Function Problem. Also the car will overheat at idle if the a/c isn't on. The thermostat gauge stays perfectly still when moving or when the a/c is on. I haven't seen the cooling fans turn on without the a/c on. If I turn the a/c on, the left fan spins for a few seconds and turns off, it will also repeat this ever time the a/c compressor turns on on its own. The a/c also cycled a lot, but today I cleaned the condenser, and tested the a/c while the condenser was still wet. The a/c ran for a much longer time, but the cooling fan didn't operate more than the few seconds. I have only seen the left fan turn on.

When I changed the head gasket, I tested both fans with a multi meter and they both had about the same resistance. I never tested if the right fan was functional, but I know the problem is more than just a bad fan, if the fan is even bad. 

A few weeks ago, the fuse for the a/c compressor was melted, but only the plastic. I replaced it and since then it has been fine. Also, since I got the car, a 15 amp fuse has been used, instead of the 10 amp that should be. I have tried putting in a 10 amp, and it blows as soon as the a/c is turned on. I took a closer look at the wiring to the four relays, and I noticed that someone added a wire between 2 different relays. The wire tap connector they used also melted. Also, the wire used to make the jump is a solid wire, and it doesn't feel like the wire has any insulation on it. If I remember correctly, and I can check tomorrow, the wire jumps between relay number 4 and relay number 2. From what I understand, the 4th relay controls the a/c clutch, and #1 and #2 each control one fan. I still don't understand what the 3rd relay controls. 

 

My goal is to return this wiring back to the factory set up, which I assume would just be taking away the two wire tap connectors. The only reason I didn't do this yet was because I don't know why the jumper wire is there, and if its going to cause more problems than I already have. The previous person to work on the car may have used this wire to fix a different issue, which I am unaware of right now, unless it was just a bad relay, which I already replaced. I know when I went to buy the relays to replace the bad one, they were very difficult to find, and no auto parts store had them, even to order. I am assuming the 10 amp fuse blows because it is now powering the a/c clutch and a cooling fan. I also want to get the fans to operate the way they should. How should these fans operate anyway? Is it the left fan is triggered by the engine temperature senor, and then the a/c turns on both fans? 

 

Pictures of the wires for the relay: https://www.dropbox.com/sh/9bac62o9qeid86w/AAB92U7Fg2NMY6bsfHdGfBnna?dl=0

 

I would also like to add, from my knowledge, the car only had one previous owner. From what I have seen on the car, the person that worked on it did a terrible job. Like the timing belt was changed, and one of the camshaft pulleys is missing a piece, which I am guessing was broken when it was dropped. I also had to change the front wheel bearings, more predictably, the right wheel bearing. I noticed that the right front axle nut was not notched to prevent it from backing off. I also noticed that the left outer tie rod end boot was pierced with a tie rod separator. The crankshaft woodruff key was sheared at some point, and the person used a lot of washers on top of the harmonic balancer. I don't know the function of those washers, but I removed them when I did the head gasket, and haven't had any problems. There is more stupid stuff also, but I just gave these as an example of this persons handiwork.

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Remove the jumper. Whatever the issue is, we can figure it out and fix it properly.

 

Under the dash on the drivers side there are two bright green plugs. Connect them, and turn the key to On. This puts the ECU in Test. Mode, which will cause it to cycle the radiator fans through low, high, off in about 1-1/2 second intervals.

Each fan has two relays, one for each fan speed. 4 relays total. The computer grounds the coil of the relays to engage the fans. Determining which relay is for which fan and which speed can be done by removing one relay at a time to see which fan is affected. They're all the same relays so if one fan or speed doesn't work, they can be swapped around to check for a bad relay.

 

If one fan doesn't work, unplug it and check for damage or corrosion in the plug. Check for 12v going to the connector while in test mode. Two of the wires should show 12v when the relay for that wire is engaged. One wire is high speed, the other is low. The third wire in the plug is the ground for the fan. Check for continuity to ground on that wire. Also you can check for voltage on the ground wire while in test mode by back-probing the connector with a paper clip or pin. If the ground wire shows 12v there is no ground. Grounds are on the inner sides of the frame just a few inches from the fans.

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I did some testing while in Test Mode. I didn't remove the jumper yet, I am at work and will do tonight when I am home, so I can cover up the 

 

The left fan only spins at one speed.

It receives 12 volts on the outer wire. The middle wire doesn't receive any voltage. I did notice that the multi meter changed to 0.1 volt n sync with when the fan should be on.

I swapped all the relays around, and the middle wire still didn't receive any voltage. I could also feel that all the relays switched on and off.

The resistance of the fan was 1.1 ohm on both the outer and middle wire.

 

The right fan does not spin at all.

The right fan received 11.X volts on both the outer and middle wire. I did check the battery, and its reading high 12.7ish volts.

The resistance on this fan was 16 ohm and 60 ohm.

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The fan with the low resistance readings may have some shorted windings which would cause high current to flow. That may explain the need for the larger fuse. You may need to replace the fan. If you don't have a factory service manual for the wiring I suggest you get one. Ebay is a good place to get one. It will make things a lot easier to work on.

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Might try tapping (and by that I mean smack the hell out of it) the right fan motor with a screwdriver handle to see if maybe the brushes are just stuck. If they are, this may temporarily loosen them and make the fan start working. The fan will need to be replaced to be reliable.

If that doesn't make it work, make sure the fan has a good ground. You might even try running jumper wires directly to the fan from the battery (be sure to use a fuse).

 

No voltage reaching the left fan could have something to do with the jumper, or could indicate a wiring problem elsewhere.

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Took another look at the pics and compared with the wire diagram in the FSM. The jumper is tied to the brown and red wire, which comes from the 10 amp fuse, which is only supposed to power the relay coils. He's tied that to the white and Blue wire, which is the power for the low speed? on the left fan.

It looks like its wired so the fan should run anytime the ignition switch is On.

The 10 amp fuse in the relay block is the one that keeps burning right?

 

 

The 20 amp fuse right next to it is the main power for the left fan. This supplies 12v to the White wires that go to the relays. Make sure the fuse is good, and make sure 12v is reaching the relays on the white wires.

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Oddly enough, the fan with the lower resistance is the fan that works, at least on one speed. I would think if the resistance was as low as 1.1ohm when it should be around 16 ohms, it would be tripping even the larger fuse, or not even run.

I have a copy of the FSM, just haven't found the diagram for the fans yet, I just know one fan is 120 watts, and the other is 140 watts. This would mean one fan would pull about 10 amps and the other would pull 12 amps at full speed.

 

I am wondering if the right fan is not moving because of an electrical issue. It is receiving lower voltage than it should be, which might also mean it is not getting enough amps to run. I'm going to try running each fan on battery power in the next few days when I have some time.

 

Since the fans share the ground for both the high and low speeds, it probably isn't a ground problem for the left fan, although the right fan might have a ground issue. I do think its slightly unlikely as the two fans ground share a common ground,  but I'm not sure without looking. I will try to check the ground wires when I check the fans.

The relays would also then switch the positive wire, which is typical in most cars. 

 

Yes, the 10 amp (which is now 15 amp) is the only fuse that ever had a problem. 

The 20 amp fuse is good, I just checked it. I will check the white wire to make sure its getting 12 volts.

 

I will also have to check the wire tap connector locations, I'm wondering if maybe the wire is corroded now from being exposed, the main reason I never trust these connectors, especially in cars.

 

I just found the diagram for the fans. If I'm reading it correctly, it's only showing 3 relays, and the 3rd relay controls the sub fan lo and high speed, with another relay somewhere else in the system. I will have to take a better look at this when I have a little more time.

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Right. The 4 relays in the underhood box are the AC compressor relay, main fan 1&2 (Low and high speed) and sub-fan 2. I had forgot the sub-fan 1 relay was inside in the dash fuse panel or I would have mentioned that before.

 

Sub-fan or AC sub-fan is the one on the right. If you think it may be an amperage issue check voltage at the plug with the fan plugged in.

The fuse for the sub fan is in the dash fuse panel. But since you have voltage reaching the fan plug, the fuse and relay are probably fine.

 

 

I don't like to see those crimp on splice connectors either. They're quick and easy, which is why people use them, but they leave the wire open to corrosion and they cut some of the strands which lowers the capacity of the wire. In most cars the wiring is already designed to just barely handle the amount of current in the circuit because copper is expensive. Losing 10% of a wires carrying capacity can cause a lot of heat from all those electrons trying to squeeze through.

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Well if the fans are rated for the amount of power you stated then the fan with the high resistance must be bad. There is no way it could work like it should.

 

If the middle wire on the working fan is the power wire for the other speed then you need to check the voltage on the switched contact of the relay that controls that speed when the fan is supposed to be ON. If the voltage is good at that point then there is an bad connection between there and the connection to the fan.

 

Good to hear you have a factory manual to refer to. You should be able to find the information on the fans in the AC and engine sections of the manual.

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I tested both fans last night, and both are working on both speed. I retested the resistance on the right fan, and it was 1.x today. Maybe the multimeter was getting a good reading with the original test inside the car, and last night I did it outside the car. 

I also noticed the left fan only runs when the a/c is on and the engine temp is at the trigger point for the fans. 

 

I check the fuse in the inside fuse panel for the main fan, and that was fine. I switched it with the door lock anyway, just to make sure. I did see 3 relays above the  fuse panel, and i checked the owners manual but its not listed what those relays are for. I will try checking the service manual tonight.

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Three relays way up in the corner are the fuel pump, main relay, and the blower motor relay.

 

So you jumpered the fans to the battery and they all worked?

 

The left fan (main fan) will only engage by itself when the engine coolant temp reaches 204°F.

I believe both should run when the AC is on.

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I have some time off today, so I am taking a closer look at everything.

All fans are working when connected to the battery. I also jumped the fans from the relay terminal just now, and the fans work from that.

The 2 main fan relays and the sub fan relay #1 all have battery power to the switch side of the relay. Sub fan relay #2 looks like it gets its switch power from the line that goes from sub fan relay #1 to the fan. I'm assuming sub fan relay #1 is the low speed, and #1 and #2 together are high speed.

 

I did remove the jump wire, the white with green wire was fine, and i'm just going to throw heat shrink over the pierced part of the wire.

The brown with red wire was a little burnt looking, so i cut out that section and going to crimp it together and cover it with heat shrink.

 

I retested all the relays and they are good, i checked the fuses and those are good too.

 

When I was looking for the sub fan relay #1 under the dash, I noticed that there was more wire spices.

I will take a better look at which wires are spliced to where.

I also noticed some wires that run next to the fuse block that look at out place (red and blue wire), that i'm not able to see where they go yet.

 

Update:

After taking a better look under the dash, I noticed any spiced in wires and the two out of place wires were installed for the keyless remote / alarm system. I'm slightly surprised the dealership would do such a sloppy job since I am assuming it was ordered at the time of purchase.

Edited by turodoggy
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  • 7 years later...

I think it's hilarious that all this discussion about the relay is had here and nobody explains where the interior fan relay is at!

I'm noticing on my 96 Legacy I have the same issue and nobody approached the relay location?!?

 

Edited by iriejedi
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