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Cooling Fan Help

11K views 19 replies 5 participants last post by  tarzan007 
#1 ·
I have a 2003 Outback Wagon and the cooling fans are not coming on. I have verified that both relays work and the fans themselves also work. The two 30 amp fuses in the engine compartment fuse box are also good. The wiring diagram says there are 2, 15 amp fuses that supply the control side of the relay. I am not getting any power to the control side of the relay and suspect these fuses are blown. But I can not find them! They are not listed in the passenger compartment relay box. The diagram calls them fuse 17 and 18.

Any thoughts on where these are located?
 

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#3 ·
Is this a 4-cylinder or 6-cylinder engine? Also, is the car a North American model, or elsewhere?

The partial wiring diagram that's attached appears to be for the 4-cylinder, but if it's a 6-cylinder, the set up is different.

In both cases, fuses 17 and 18 are in the cabin fuse box, identified in the Owners Manual as

17 15A Air conditioner
18 15A Backup light, Cruise control, ABS (VDC) control

but the other two fuses, in the engine compartment are 20 Amps for the 4-cylinder, 30 Amps for the 6 cylinder.

Also, the 4 cylinder has two relays to control the radiator fans; the 6 cylinder has 5.

Under what conditions are the fans not coming on? Is the engine overheating?
 
#4 ·
It is a four cylinder, north american model. I did check both of those fuses you listed (17 &18) as well as the two in the engine compartment and they are all good. The fans just don't come on at all anymore. I am the original owner of this car and I remember the fans coming on after I would park the car on hot days or long drives. Now, nothing. The car did overheat once but there was a crack on top of the radiator. I changed out the radiator and the car is not overheating but the fans are not coming on like they should.

I can get the fans to turn on by pulling the relays and jumping the high current side. I just cant measure any voltage on the control side of the socket in the fuse box. I actuated each relay manualy and they do close when I put voltage to the control side.

Any thoughts? and thanks for the quick reply.
 
#5 · (Edited)
Is the wiring diagram you're using for the 2003? I've attached a wiring diagram for the 4-cylinder rad fan system that's somewhat different in layout, and might have different connecting pin numbers.

I am the original owner of this car and I remember the fans coming on after I would park the car on hot days or long drives.
If the car is parked with the ignition key at ACC, OFF, or out altogether, the fans should not run. While I suspect this is just a question of clarification, if indeed the fans did run, I'd be suspicious.

(The reason the fans should not run is that the relay energizing coils are powered from the ON (or IGN) terminal of the ignition switch. With the switch at ACC or OFF, there should be no continuity through the switch to the relay coils.)

I can get the fans to turn on by pulling the relays and jumping the high current side.
Referring to the diagram I attached, I presume you're jumping between pin 8 and 9 of the Main relay, and pins 21 and 20 of the sub-fan relay. Is this correct? If so, that's a good test of the main fuses, wiring and fan motors. (At the bottom of the attached page there's diagrams of the connectors F66 and F28 with their corresponding pin numbers.) As the two main fuses at F27 are always powered from SBF-1, jumpering the high current side would turn the fans on even with the ignition switch OFF.

Incidentally, the two main fan fuses are shown in the diagram, and in the Owners Manual, as 20 Amps, rather than 30 Amps as you mentioned in the first post.

I just cant measure any voltage on the control side of the socket in the fuse box.
Can you identify in the attached wiring diagram where you're measuring (connector and pin numbers)?

Pending your clarification, I'll jump ahead and presume you're not finding any voltage at pins 5 and 7 of the main fan relay, and pins 24 and 22 of the sub-fan relay. Are you measuring with the key at ON? Otherwise, there's no power to fuses 17 and 18 and therefore no power to the relay coils.

Fuses 17 and 18 power other functions in addition to the two rad fan relay energizing coils. For example, fuse #17 also powers the cabin heater/AC fan motor relay. A quick check for power at fuse #17 would be to turn the ignition switch to ON and turn on the heater fan. If it works, then fuse #17 is powered. Similarly, fuse #18 supplies the power window relay, so with the ignition key at ON, if the power windows work, then the fuse has power.

Alternatively, with the key at ON (engine need not be running), there should be battery voltage at fuses 17 and 18. Have you checked at both sides of each fuse? (The mini-fuses have small openings in the back of the plastic case where the tip of a meter test probe can contact the fuse to measure voltage at both sides while the fuse is in place. There should be 12 V at both sides of each fuse, relative to ground.)

I actuated each relay manualy and they do close when I put voltage to the control side.
Good check -- to be sure the relays do activate when battery voltage is connected across the energizing coils.

Okay, so let's get things clarified so we're on the same page, and we'll go from there . . . There could be a problem with the engine coolant temperature sensor connection between the sensor and the ECM, but that's high on the list, at least not initially . . .

p.s. There's a pair of green connectors under the dash that, if connected (they're normally not), will cause the ECM to cycle a number of relays and solenoids, including the fan relays. This could be something worth trying. This thread refers to them at post #14 and beyond, with a diagram of their location. Might be worth trying as it checks the rad fan system from the ECM on and avoids the need to rig up jumpers etc. If it works, and the fans cycle on and off (as long as the key is at ON), then pretty well all the downstream circuitry is good. The need then would be to find out why the ECM isn't turning them on when the engine temp rises.

Incidentally, do the fans turn on (one or both) when the engine is running but not "overheating" and the AC is turned on?
 

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#6 ·
Thanks for the wiring diagram, it's very helpful.

Well, I warmed it up this morning and everything seems to work fine. The cooling fans kicked in when the AC was turned on. THey also kicked on when I was idleing with the AC off. You are correct that there is only power to the relays when the key is turned on. I must have been mis-remembering that the fans would stay on when the car was turned off (sucks getting old).

Thank you for your very detailed and informative replies. They were extremely helpful
 
#8 ·
Fans wont kick on , even with a/c on



Hello All:

my car overheated -2002 legacy wagon

I was down 1/2 gal of fluid..refilled with fluid

I noticed my fans were not coming on at all.

Even If I turn the A/C on my fans will not come on.

The 2 fuses and the 2 relays in the engine compartment are fine, as I re positioned the relays.

If I remove relay and jumped the terminals. I can get both fans to come on.

1-What do I do next?
2- do the cabin fuses cause this?


thank you

Dean
 
#9 ·
2- do the cabin fuses cause this?
If they are blown, yes, they could.

If I remove relay and jumped the terminals. I can get both fans to come on.
Need more info on what socket terminals were jumped. Reference the wiring diagram attached in post # 5 above (if yours is also a 4 cylinder).

1-What do I do next?
Do you have a multimeter that you can use to measure voltages etc?

If yes, then with the two relays removed, engine off, key at ON, is there 12 V (measured to ground) at pins 7 and 5 of the main fan relay socket, and at pins 18 and 20 of the sub-fan relay socket?

Even If I turn the A/C on my fans will not come on.
Turning the A/C on in the cabin doesn't necessarily mean that the A/C compressor is turned on (i.e., the compressor clutch has been engaged). Are you sure it's actually running? (The A/C compressor is not turned on if the ambient temperature is at or near the freezing point. And, of course, the engine has to be running.)
 
#10 ·
more info

the a/c compressor relay solenoid side has no power at all.

the fans have power on the solenoid side of the relay, but wont turn on.

my friend is helping me today

Dean
 
#11 ·
Does the cabin HVAC fan work?

the a/c compressor relay solenoid side has no power at all.
If it has no power, then the A/C compressor clutch won't work = no A/C cooling.

If the HVAC fan does work, then the A/C compressor relay might not have power because the refrigerant pressure in the A/C system is too low, perhaps because it has leaked out. Did the A/C ever work?
 
#12 ·
its not the freon,

" I can jumper the ac power wires and it works, the solenoid side isnt getting 12 v"

does this make any sense?

I appreciate this ..

Dean
 
#13 ·
" I can jumper the ac power wires and it works, the solenoid side isnt getting 12 v"

does this make any sense?
If you're overriding the A/C compressor relay to force the clutch to engage, then you might also be overriding the A/C's self-protection system. My question about the cabin fan might provide some leads . . .

The A/C relay solenoid coil is powered from fuse #17, which also powers the radiator sub-fan relay solenoid coil, and, the cabin blower motor relay solenoid coil. So if the cabin fan works, then there's power to the other two coils. However, the power for the A/C relay also has to go through the A/C pressure switch, which, if the refrigerant pressure is low, will open that circuit so that no power would get to the A/C relay. So, I repeat, does the cabin fan work? If not, check the fuses in the cabin fuse box.

its not the freon,
How was this determined?
 
#15 · (Edited)
yes, cabin fan works.
That confirms fuse #17 is good.

As far as the A/C compressor relay not having any power on it's solenoid coil, the next thing to check is the A/C pressure switch. The power from fuse #17 has to go through this switch to get to the A/C compressor relay solenoid coil. It has only two wires to it, and there should be continuity (pretty well zero resistance) between the switch connections. If it's not zero resistance, then that's where the power to the relay is being blocked, and that's probably because the pressure is not correct (although it could also be a defective switch).

(edit) Alternatively, if you can back probe the two wire connector at the A/C pressure switch, check if there's 12 V at both wires (i.e., not just one), as there should be, when the ignition key is at On.


Going back to the radiator fan issue, did you do this test:

. . . with the two [radiator fan] relays removed, engine off, key at ON, is there 12 V (measured to ground) at pins 7 and 5 of the main fan relay socket, and at pins 18 and 20 of the sub-fan relay socket?
If there is 12 V at those points, the next step would be to see if the ECM control of the fans is working. There's a pair of two-pin green connectors under the dash on the left (driver) side, close to the transmission hump. The connectors are normally not connected. With the ignition Off, connect them. Then turn the ignition to On. This should result in the ECM switching a number of relays and solenoids, including the radiator fan relays, on and off continuously in cycles. If the fans run cyclically as the ECM goes through the test sequence, then the ECM ability to control the fan relays is good. (Turn the ignition Off and disconnect the green connectors after the test.)
 
#18 ·
That confirms fuse #17 is good

(edit) Alternatively, if you can back probe the two wire connector at the A/C pressure switch, check if there's 12 V at both wires (i.e., not just one), as there should be, when the ignition key is at On)
There was only voltage at one wire of the Ac. Pressure switch, I think it was the yellow one with voltage
 
#16 ·
1- The fans will come on if I short out to plastic 2 wire AC terminal that fits into the AC pressure switch.
2- The AC pressure switch has an open contact across the terminals , where it threads in at the Cylinder
3-there is sort of a greasy like -sticky substance on my AC lines

I would post some pictures but for some reason I don't have authorization from the site

Thank you wizard for helping me


I don't know anything about Ac, but if the AC pressure switch is not working then neither of the fans will work.
 
#17 ·
Update w photos

1- photo shows shorting out 2 wire terminal at pressure switch to get fans to run- fans now run normally

2- photo shows greasy stuff on Ac lines????? What is it

3- photo shows open contact at Ac pressure switch with a reading of "1" across terminals at cylinder

All relays and all fuses are good

All power is good at the pins ,when relays are pulled
 

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#19 ·
If the pressure switch is open, it's more likely the pressure in the A/C refrigerant lines is too low. The greasy stuff on the A/C hose could be a sign of leakage from that fitting. It's not unusual, especially on an older car. And that would explain why the A/C compressor doesn't run, and possibly why the radiator fans don't work when the A/C switch is turned on in the cabin.

However, the open pressure switch does not have any impact on the operation of the radiator fans in regard to engine temperature. The fans are controlled by the ECM. The ECM does not consider whether or not the A/C pressure switch is open or closed, or even whether the A/C is on or not, when it has to correct for the engine coolant temperature being too high.

At this point I'd disregard the A/C -- the loss of pressure in that system can be dealt with separately. I'd suggest that you try the operational test with the green connectors. If that works, then the problem might be with the engine coolant temperature sensor system; either the sensor itself or the wiring between it and the ECM. (The goal here is to deal with the report that the fans do not come on when the engine is overheating. We know why the A/C doesn't work. That's something else.)
 
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