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Old 06-19-2010, 10:39 PM   #1
kirbykirb
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Default Fans don't come on until I turn on AC? By fans I mean the ones by the radiator...?

So basically, the car is a slight heating issue. It doesn't overheat but the fans don't come on by themselves until I turn on the AC, otherwise if the AC is off it is only cooled by the coolant, rad and passing air which in turn isn't good enough so I always have the AC on. :P

But, wiring is imo good because it turns on with the AC, and I also assume the relay is good because if it was a bad relay it wouldn't work if the AC was on.

So, is there a temp sensor which can fix this? And where would it be?

Thanks.
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Old 06-19-2010, 10:48 PM   #2
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Does the car overheat?

Fans on with A/C is normal.
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Old 06-19-2010, 11:28 PM   #3
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Originally Posted by KillerBMotorsport View Post
Does the car overheat?

Fans on with A/C is normal.
The gauge goes up yes, but overheat, I wouldn't say so... but it does get up there pretty high, i've also lifted the hood when it was up all the way and no fans.

Coolant has no bubbles in it, going to replace radiator cap anyway for safe measure

Thermostat is going to be replaced as well, but I'm thinking it is a temp sensor or something...
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Old 06-19-2010, 11:35 PM   #4
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Does the gauge go higher than half way? It doesn't really sound like you're overheating.

The temp sensor is probably cheap and easy to replace. Easy place to start.
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Old 06-19-2010, 11:41 PM   #5
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Does the gauge go higher than half way? It doesn't really sound like you're overheating.

The temp sensor is probably cheap and easy to replace. Easy place to start.
Yeah, over halfway, it stands a bit before the needle on top but it will get there if I drive long enough like 10/15 mins and dont' put the AC On.

If the needle is at a high point, but if I put the AC on, the needle dramatically drops down to middle point. like within 20 seconds or so, visible movement of the needle.
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Old 06-20-2010, 08:39 AM   #6
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Not sure how replacing the thermostat and radiator cap are going to do anything to help that. You're just going to be wasting time and effort doing work that isn't going to fix the problem.

Quote:
Originally Posted by kirbykirb View Post
Yeah, over halfway, it stands a bit before the needle on top but it will get there if I drive long enough like 10/15 mins and dont' put the AC On.
Huh?

One of the fans should come on around 92*C or somewhere in that ballpark. (That's based on watching my coolant temperature gauge, which is a real gauge, not the factory dummy.) Based on what you've described, there's some sort of electrical/wiring/sensor issue that isn't triggering the fan. Or, it's possible that the sending unit for the dummy gauge in the instrument cluster is bad and the indication you're seeing in the dash just isn't accurate. If you can find someone with an OBD2 datalogger it would interesting to see what the ECU thinks the coolant temp is (the instrument cluster and the ECU get their temps from two different sending units). Honestly, I would say more likely that you've got a bad indication rather than a bad ECU.

Pat Olsen
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Old 06-20-2010, 09:18 AM   #7
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Would a bad sending unit trigger a CEL? You'd definitly see it on datalog.
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Old 06-20-2010, 09:34 AM   #8
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The gauge sending unit doesn't interface with the ECU at all, so no. Not sure if a bad coolant temp sensor (the one that actually feeds the ECU) would somehow trigger a CEL if it always read lower than expected or something like that.

On my car, the stock dummy gauge sits just below 1/2 way when it's at steady state. It gets to that point by about 70*C and doesn't budge from that point until at least 100*C (based on the readings on my real gauge). Unless you have some reason to think your cooling system is jacked up, kirb, I think it's more likely that the dummy gauge is giving you an improper indication.

Pat
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Old 06-20-2010, 09:54 AM   #9
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The gauge sending unit doesn't interface with the ECU at all, so no. Not sure if a bad coolant temp sensor (the one that actually feeds the ECU) would somehow trigger a CEL if it always read lower than expected or something like that.

On my car, the stock dummy gauge sits just below 1/2 way when it's at steady state. It gets to that point by about 70*C and doesn't budge from that point until at least 100*C (based on the readings on my real gauge). Unless you have some reason to think your cooling system is jacked up, kirb, I think it's more likely that the dummy gauge is giving you an improper indication.

Pat
That's what I've been meaning, the dummy guage is being mean. :'(

kinda sad it's another dummy gauge like the miata oil pressure sender, fake. D:

So, just to be clear? Theres a sending unit just for the dummy guage right?

BTW, just saw: http://www.submariner.org/thepno95/P...%20sensors.jpg Thanks for the pic

So this will be on the passanger side of the engine right? Somewhere right around the intake manifold? :P
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Old 06-20-2010, 11:58 AM   #10
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Yes, the two sending units are on the passenger side of the coolant crossover that runs under the intake manifold. Kind of a PITA to get to with the intake still in place.
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Old 06-20-2010, 03:30 PM   #11
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Yes, the two sending units are on the passenger side of the coolant crossover that runs under the intake manifold. Kind of a PITA to get to with the intake still in place.
Perfect, thank you. ;D

Going to go check if hteir loose, it's if it isn't going to replace it!

THANKS

But this wouldn't deal with the fans turning off/on would it?
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Old 06-20-2010, 05:59 PM   #12
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IMO you have one of two possibilities:

(1) The gauge sender is bad. The actual coolant temperature is perfectly normal, but the gauge sender is showing that the car is overheating. The fan isn't coming on because it doesn't need to; the actual temperature is normal, and the ECU sees the normal temperature because it gets its temperature inputs from a separate sending unit. Or...

(2) The gauge indication is correct. The ECU isn't triggering the fan to turn on because either (a) the coolant temperature sending unit is reading incorrectly and telling the ECU that temps are fine, or (b) there's some other fault in the ECU that isn't triggering the fan to turn on.

IMO (again), (2b) is rather unlikely. So (1) or (2a) are your most likely issues. If you can find someone that can datalog your OBD2 port, you should be able to pretty quickly see if (2a) is the problem - the coolant doesn't take very long (only a couple of minutes) to get up to normal temperature. If a datalog shows that coolant temp is just hanging out at ambient temperature or something abnormally low, then the coolant temperature sending unit is bad.

You can get both the gauge sending unit and the coolant temperature sensor on rockauto.com for about $20 combined. Seems like a pretty cheap possible fix to just order them both and replace them both. It's going to cost you more in labor, since they are a pain to get to and you're going to have to partially drain the cooling system.

Pat
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Old 06-20-2010, 06:18 PM   #13
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Quote:
Originally Posted by Patrick Olsen View Post
IMO you have one of two possibilities:

(1) The gauge sender is bad. The actual coolant temperature is perfectly normal, but the gauge sender is showing that the car is overheating. The fan isn't coming on because it doesn't need to; the actual temperature is normal, and the ECU sees the normal temperature because it gets its temperature inputs from a separate sending unit. Or...

(2) The gauge indication is correct. The ECU isn't triggering the fan to turn on because either (a) the coolant temperature sending unit is reading incorrectly and telling the ECU that temps are fine, or (b) there's some other fault in the ECU that isn't triggering the fan to turn on.

IMO (again), (2b) is rather unlikely. So (1) or (2a) are your most likely issues. If you can find someone that can datalog your OBD2 port, you should be able to pretty quickly see if (2a) is the problem - the coolant doesn't take very long (only a couple of minutes) to get up to normal temperature. If a datalog shows that coolant temp is just hanging out at ambient temperature or something abnormally low, then the coolant temperature sending unit is bad.

You can get both the gauge sending unit and the coolant temperature sensor on rockauto.com for about $20 combined. Seems like a pretty cheap possible fix to just order them both and replace them both. It's going to cost you more in labor, since they are a pain to get to and you're going to have to partially drain the cooling system.

Pat
Labor is fine, I'm sure this is something I can DIY from overlooking the FSM. Draining the coolant is not a big issue, and I haven't touched it since the PO did it which I have no idea, so it's good time for a flush (plus a new thermostat!)

I hate to be a burden, but Patrick: anyway I can get you to provide P/N's for both sending units? Since I'm in there I'd rather replace both then just one, I learned the other day when working on a friends car with the radiator/codensor out that I should've taken advantaged of the "more open space" and re tensioned the belts and replaced an ac compressor, sadly I didn't and looks like I'd be helping him with that again. :P (not a subie btw!).

Hehe, thanks so much for providing the assistence I so needed to get my subie to play nicely.
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Old 06-20-2010, 08:12 PM   #14
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I hate to be a burden, but Patrick: anyway I can get you to provide P/N's for both sending units?
I don't have access to part numbers if you're looking for the Subaru parts. Just go to www.rockauto.com and order them from there. Very simple site to use, just select Subaru, your model and year, and look in the Cooling System section and you'll find 'em.
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Old 06-21-2010, 12:12 PM   #15
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it could be that the radiator temperature sensor has gone bad, do you have multimeter?
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Old 06-21-2010, 12:28 PM   #16
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there is no sensor in the raditaor.

The sensor that sends temp info to the ECU ( prong) is probably reading inaccurately. They can do that, and when they do, they don't always throw a code.

I would test it's resistance when the car is warm (gauge halfway)...it should be between around 300-500 ohms......any more than that is an inaccurate reading.

If that is correct then likely the gauge sender is off.

of course, there is a very unlikely possibilty that the circuit in the ECU that drives the fan relay is shot.

And BTW, it would be easier to help if we knew an excact year engine for your LEgo.
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Old 06-21-2010, 12:50 PM   #17
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there is no sensor in the radiator.
im no subaru expert, some cars (Older) do. i just meant the coolant temp sensor (for the fan)

Last edited by Murphy's Law; 06-21-2010 at 03:24 PM. Reason: me having a bad brain
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Old 06-21-2010, 01:31 PM   #18
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there is no sensor in the raditaor.

The sensor that sends temp info to the ECU ( prong) is probably reading inaccurately. They can do that, and when they do, they don't always throw a code.

I would test it's resistance when the car is warm (gauge halfway)...it should be between around 300-500 ohms......any more than that is an inaccurate reading.

If that is correct then likely the gauge sender is off.

of course, there is a very unlikely possibilty that the circuit in the ECU that drives the fan relay is shot.

And BTW, it would be easier to help if we knew an excact year engine for your LEgo.
Oh, thought people read it from my profile.. :P EJ25D It's thr 95/96 year so has that loving premium only with 10hp less from later years.
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Old 06-21-2010, 01:41 PM   #19
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assuming both fans actually come on and run when the AC is turned on, which is what it sounds like from the first post, then you can rule out a bad fan / wiring connector.

if it is your ECU temp sensor i'm surprised you don;t have other issues like hard to start or ....?????

maybe try disconnecting the 2 wire temp sensor (ecu) and see what happens.
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Old 06-21-2010, 02:03 PM   #20
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Originally Posted by jegg View Post
assuming both fans actually come on and run when the AC is turned on, which is what it sounds like from the first post, then you can rule out a bad fan / wiring connector.

if it is your ECU temp sensor i'm surprised you don;t have other issues like hard to start or ....?????

maybe try disconnecting the 2 wire temp sensor (ecu) and see what happens.


Well, when it starts up yeah sometimes I crank it and it won't startup; I'll have to turn off AC, put fan on one, turn off headlight, foglight, etc for it to turn on.

Not the battery btw, have had to charged and inspected and also even replaced it to be safe. I've always assumed it was the starter bushings and had it to my list. :P

But this hardly happens like maybe once/twice in a week IF that.

Anyway going to order both sensors today hope I don't have to remove the intake manifold when I swap them out.
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Old 06-21-2010, 02:08 PM   #21
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Originally Posted by Patrick Olsen View Post
I don't have access to part numbers if you're looking for the Subaru parts. Just go to www.rockauto.com and order them from there. Very simple site to use, just select Subaru, your model and year, and look in the Cooling System section and you'll find 'em.
Hmm, so I buy one of these...



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Old 06-21-2010, 05:13 PM   #22
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Well, when it starts up yeah sometimes I crank it and it won't startup; I'll have to turn off AC, put fan on one, turn off headlight, foglight, etc for it to turn on.
so the engine turns over but it does not fire??

does it do this when it's hot, meaning you drove the car, warmed it up and then turned it off? on re-start it would not fire?

this is a symptom of a bad ects, the ecu thinks the car is cold when it is really warmed up. it probably is running rich.
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Old 06-21-2010, 05:16 PM   #23
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Hmm, so I buy one of these...
you want the 2 wire unit for your year with the brown connector . the one wire unit is for the temp guage.



subaru part number 22630AA041, they used this on every legacy, impreza and forester they built in the 90s, probably still using it.

check your local parts house, it may cost a little more, but you will not have to wait.

item #1 below, it looks like it threads in from the rear???

http://opposedforces.com/parts/legac.../water_pipe_1/



Last edited by jegg; 06-21-2010 at 05:30 PM.
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Old 06-21-2010, 06:12 PM   #24
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you want the 2 wire unit for your year with the brown connector . the one wire unit is for the temp guage.
I still think he should get both. Even if the ECTS is bad, and the fans aren't turning on because the ECU doesn't think the coolant is hot, the cooling system should be able to maintain temperature when the car is in motion. The fact that he's getting indications of the car overheating on the temperature gauge makes me think it's more likely the gauge sender is bad. And since it's just as much of a PITA to replace one as it is to replace both, I think he should replace them both.

Quote:
Originally Posted by jegg View Post
item #1 below, it looks like it threads in from the rear???
Yup. Like I said, it's going to be a pain in the arse to get to with the intake manifold still in place. I think it's do-able, but it's going to require some cursing.
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Old 06-21-2010, 06:41 PM   #25
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so the engine turns over but it does not fire??

does it do this when it's hot, meaning you drove the car, warmed it up and then turned it off? on re-start it would not fire?

this is a symptom of a bad ects, the ecu thinks the car is cold when it is really warmed up. it probably is running rich.
Actually I think the engine/starter isn't running, it's as if it was a dead battery issue. I don't believe it to be related but since you asked I stated it...

As for when it occurs, usually yes after I park somewhere and come back and turn it on. I think the starter just doesn't turn over so nothing, the engine def doesn't try to start, just like a dead battery (but in reality is fine, but it's weird since the starter was replaced with a napa unit sometime in the past 3/4 years ago so it is pretty new'ish, hmm.

But yes I think the car is running rich as well, though it does get a bit above average mpg, I traveled over 340 miles on 14 gallons roughly.. highway though not city, city it drops to between 18-20 IMO. Mind you I am not sure, I do a pretty inaccurate reading of resetting the trip odometer, and then filling the car up; see how many gallons I put into the car. Then whenever next time I stop into the gas station; I divide by how many gallons I put in vs the odometer, I could be off by a gallon or such but it gives me around 20-25 mpg usually so always counted it as accurate: THOUGH when I do an OBD2 scan the ecu was tripped for an "Inefficent cat" or something, I forgot the exact code but something to that effect.

Gash, I feel so silly and ignorant not really looking into this issue sooner. Guess I'm also going to add 02 sensors to my list of things to do. I bet their original so might as well.

So,
New Front 02 sensor.
rear 02 sensor
sender sensor
coolant temp sensor
starter (may as well not that much money for piece of mind, hopefully theres a warranty. )
woot woot!
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