cooling fan question

[mva5142]

I have a '98 OBW with 126k miles on the clock. The last few days the temp gauge has started climbing when it sits at idle for a bit. Like thru a long line in the drivethru or waiting for a while in the parking lot to meet someone. It typically holds just under the temp icon on the gauge, but when it rises, it will go up to between the 1st and 2nd mark on the temp icon.

 

Looking at it today, at idle, only the passenger side fan came on as it cycled on and off, and only the passenger side fan comes on when you turn on the a/c. With the temp only rising at idle and not while being driven, it makes sense that it is the fan, as at other times there is sufficeint air flow across the radiator to cool it down. The temps around here have been at or above 90 for a week or so and I think the problem is starting to show itself now. Anything else to look for?

 

Thanks.

 

Matt

[Rooster2]

I think you are on the right track in that both cooling fans should be operating together. If you have a multimeter or test lamp, see if you have power at the wiring connector going to the cooling fan that is not operating. If you have power, but the fan fails to operate, then if it were me, I would get a replacement fan from a wrecking yard.

 

The good news is that your problem seems to be a bad fan, and not a head gasket problem.

[nipper]

2nd fan only comes on with AC.

 

WHy not start with the simple and replace the radiator cap first?

[OB99W]

Both fans should be on with the A/C running, so it seems that your diagnosis is correct. Besides wiring/connections, check that the fan motor isn't seized, and then for power when it should be energized. If it's not getting powered, check the corresponding relay.

 

See http://www.endwrench.com/pdf/heat/CoolingFanInfoS01.pdf

[mva5142]

Thanks for the advice. I'll check connection and make sure it is getting power and then look at replacing it. A quick check showed rock auto had one for 60 bucks, vs 120 at a local parts place.

 

I'll probably throw a new radiator cap on as well, as the one on there is 12 years old. It won't hurt anything.

 

I'll let you know how it goes.

 

Thanks again.

 

Matt

[GeneralDisorder]

If one cycles with the temp and the other comes on with the AC then neither fan has failed.... but you may have a relay problem somewhere as when the AC is on both of the fans should run together. With the AC off only the passenger side fan will cycle.

 

GD

[mva5142]

General Disorder,

 

Thnaks, the drivers side fan never comes on. As you said, the passenger side cycles on and off w/out the a/c on and it is on when the a/c runs as well.

 

Will pull out the old volt meter tonight and try to find out something.

 

Thanks again for you advice.

 

Matt

[GeneralDisorder]

Ah - I misunderstood then. Sounds like the fan could have failed then or a relay is bad. Both fans run off relay's so the AC fan relay could be toast. It's probably more common for the fan motor to die though - I've seen that a couple times.

 

The fans use the same connector so all you need to do is remove the driver's side fan, slip it under the car and hook it up to the connector for the passenger side fan. Turn on the ignition with the AC/Defrost turned on and if the fan comes on then you know it's not the fan motor.

 

GD

[mva5142]

UPDATE:

 

Well I had a chance to check it out last night. I took General Disorders advice and plugged the drivers side fan into the passnegers side connecter. The fan worked. Don't know whether to be happy or sad. I was hoping the fan wouldn't work and it would be an easy plug and play to get a new one. Now I am chasing electrical issues and I can't stand that.

 

In the meantime, I spliced into the harness of the fan and wired it directly to the battery and ran a line into the car to a toggle switch so I can at least turn the fan on and off as I drive to keep the temp gauge steady. I bought a 20 amp in-line fuse to protect everything.

 

I do have to admit it feels a little redneck to have a length of wire running into the car with a brass toggle switch on it to turn the fan on and off.

 

Any advice on testing out the wiring harness to find out what the root of the issue is?

 

Thanks

 

Matt

[Fuzpile]

Hi. I have a '97 Legacy L with the same setup. It's somewhat misleading, the main and "sub" fan. Subaru did this so the sub/ac fan will double as the main one. The fact that the pgr,rside/sub fan comes on when hot eleiminates a lot of things.

[Fuzpile]

I must post quick or get cut off. My car worked the same but in this weather both fans are useful. I had checked the operation of the dormant/lside fan and it worked fine . The center terminal is ground. Refer to earliest tips and save Ur $. These are good fans. Because of what I read in manual I checked the connectors to the fans for color code against the wire diag. That was good. There was only an interruption in the ground path to main fan.

[Fuzpile]

There are 4 dedicated relays and basic fuses to check or swap and things can become more complicated. The ecm receives its heat signal. It will run whatever fan is working. Mine ran this way a while before I got it. Good machines.

[forester2002s]

Fuzpile raises an interesting point, in that many electrical problems are due to a bad ground.

 

So, have you checked that the ground wire to the A/C fan is good?

You can do this with a resistance/continuity tester, or you could run a temporary good ground to the appropriate connector.

 

It's worth a try.

[mva5142]

I haven't had an opportunity to check much yet. After I realized the fan was still good, my priority became getting it working so that I didn't have to worry about it overheating. Now that it is set up to run off the toggle switch, I can try to diagnose it. I really can't stand diagnosing electrical stuff, but I will definitely check the ground. Probably do as you suggest and wire a good temporary ground in and check it. If that isn't it then who knows!

 

Thanks for the advice. I really appreciate it.

 

I'll keep you guys updated as to what I find out.

 

Matt

[Fuzpile]

Just a sideline; don't know if it's important. The Haynes says to make sure the "ground wire" to the radiator is good. My '97 doesn't have one and doesn't need one for fans. That spurred me to check with a DVM anyway and there was not a ground on it, in the normal sense. What I saw was more measuring thru a semiconducter where there was less resistance one way than another.

That leads me to think there is another sensor in the cooling units. Stuff works fine so i didn't persue it.