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Last night after driving home and using defrost a little I noticed that after I turned the car off the fans remained on, and on high. I noticed and thought it was a little strange, but ended up going in and not thinking about it the rest of the night (I know some cars will have a fan run on LOW for a while sometimes). Came out this morning, dead battery. I hooked up jumper cables to my wife's car (2003 ZX3) and the fans kicked on as soon as I connected my car..... I could NOT get my car started! Even holding her RPM around 3K, my car didn't have enough to turn over! I SHOULD have checked how old the batter is but I haven't yet and now I'm at work without the car.

Let's start with the fan problem, is it safe to say it's R15, the high speed fan relay? I've pulled it found continuity between 2 of the 5 legs. Is there a diagram that tells what normal is and shows what should be what when testing it? Should I even test it or assume that IS the problem and just replace it?

As far as the battery / no start. Would the fan being on while it's trying to jump take enough to where the car won't turn over? I did notice it's a 70A relay.

Thanks in advance, I've been able to get SO much done with the help of this site!

Car: 2004 ZX5 Zetec 175K miles, I bought it in Sep with 173K [wrenchin][wrenchin]
 

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...is it safe to say it's R15, the high speed fan relay? I've pulled it found continuity between 2 of the 5 legs. Is there a diagram that tells what normal is and shows what should be what when testing it? Should I even test it or assume that IS the problem and just replace it?
My '04 has four relays (R9, R10, R15, & R16) that operate the fans. On mine the high speed fan relay is actually R9.

It seems clear that you do have a relay with the contacts welded together on it and that it is causing your fans to run with the car off. You will need to replace it.

The two larger terminals on the high speed relay should NOT have continuity between them. The two smaller terminals will show continuity because that is the coil winding. Let me know if you need a better explanation and I will post a diagram.

As far as the battery / no start. Would the fan being on while it's trying to jump take enough to where the car won't turn over?
Absolutely. With the relay stuck on, your battery would be completely drained. With a flat battery it is sometimes hard to start them with jumper cables.

Also, it is not a good idea to start the car at this point. You should charge the battery using a charger first. A completely dead battery can take out an alternator, so don't try it.
 

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Discussion Starter #3
My '04 has four relays (R9, R10, R15, & R16) that operate the fans. On mine the high speed fan relay is actually R9.

It seems clear that you do have a relay with the contacts welded together on it and that it is causing your fans to run with the car off. You will need to replace it.

The two larger terminals on the high speed relay should NOT have continuity between them. The two smaller terminals will show continuity because that is the coil winding. Let me know if you need a better explanation and I will post a diagram.


Absolutely. With the relay stuck on, your battery would be completely drained. With a flat battery it is sometimes hard to start them with jumper cables.

Also, it is not a good idea to start the car at this point. You should charge the battery using a charger first. A completely dead battery can take out an alternator, so don't try it.
HUGELY helpful, thanks. Your explanation was great and that's exactly the continuity I have. Thanks for also clearing up the battery for me, that makes me feel a lot better. I have the same relays as you, but 15 was labeled "cooling fan high speed" and they're definitely on high speed which is the only reason I've zeroed in on it. Here are a couple pics of my R15.





I do have continuity between terminals 1 and 2, about 75Ω and also on terminals 5 and 7, about 565Ω. I also have 5 VDC across 5 and 7. So it's looking like this relay is actually good?
 

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Your relay would be good.

There should be no continuity between terminals 3 & 5. The smaller pin in the corner is ground for a diode that is internal to the relay.

Here is a diagram of a typical relay. Terminals 30 & 87 (you don't have 87a on your relay) would correspond to your 3 & 5. These two terminals should be open.
 

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Simplified wiring diagram for the 4 relay cooling fan system. The 4 relay system works on 3 speeds. It actually can work on 4 speeds, but I have never seen it do that.
 

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Discussion Starter #7
Thanks so much, this is all a huge help! So now that I know this relay is good I guess the next step is to test the others?
 

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I screwed up with my reply in post #4 and I have corrected it. I misread your post.

Only the two relays shown at the top of the wiring diagram can cause the fans to remain on after shutdown (your Focus should not run the fans with the car turned off). The other two relays just switch the fans from series to parallel.

It may be that the high speed relay WAS stuck closed, and in the process of removing it from the BJB it jarred it loose and it tested good. But, if the contacts are so badly burned to stick in the first place, it will happen again.

You could wait until you get your battery charged and the car running again to see what happens. You will know now that if you turn the car off and the fans stay on to pull the relay or the fuse.
 

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Discussion Starter #9
I screwed up with my reply in post #4 and I have corrected it. I misread your post.

Only the two relays shown at the top of the wiring diagram can cause the fans to remain on after shutdown (your Focus should not run the fans with the car turned off). The other two relays just switch the fans from series to parallel.

It may be that the high speed relay WAS stuck closed, and in the process of removing it from the BJB it jarred it loose and it tested good. But, if the contacts are so badly burned to stick in the first place, it will happen again.

You could wait until you get your battery charged and the car running again to see what happens. You will know now that if you turn the car off and the fans stay on to pull the relay or the fuse.
Got it! Good to know the fans don't run after the engine is cut off. And yeah I removed it and took it to work so it has def been jostled around enough to unstick it. You have been a HUGE help, thanks so much!!
 

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I have not seen that type of fan diagram before. I guess I find myself wondering which side of the upper two relays powers the 3rd speed in series? And what speed is it, an intermediate between high and low or a lower low?
 

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...I find myself wondering which side of the upper two relays powers the 3rd speed in series?
The high speed relay at the upper right powers the lowest speed.

When the two lower relays in the diagram are off the fans are in parallel and the upper two relays power high speed and medium speed. When the lowest speed is needed, the lower two relays turn on which throws the fans in series, and the high speed relay is turned on at the same time.

This gives the fans the following approximate voltages:

High = 14.x V
Medium = 9.5 V
Low = 7 V

A forth speed is possible if the low speed relay is turned on along with the bottom two relays. I have never seen this happen on my Focus. I have only seen the other three speeds, so I am assuming that speed is not programed.

On other Foci with only two fan relays, Ford did away with the bottom two relays and thus that 7 Volt speed. So, they only have high and low speeds (14V & 9.5V).

The fans are super quite when running in that 7V speed. The first time I heard them running at that speed I wasn't sure what was going on. I usually heard the high speed and occasionally the "medium" speed. I didn't know it had a lower speed until that happened.
 

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Thank you for that...............
 

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Discussion Starter #13
FocusKnot, thanks for all the info! I've learned so much from this thread!

The car is back up and running! The relay I posted (R15) didn't seem to be the one. I pulled R9 from the box to stop the fans. I put it back in after pulling it and it has worked fine since so I have a feeling that's the one going bad.
 

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...(R15) didn't seem to be the one. I pulled R9 from the box to stop the fans. I put it back in after pulling it and it has worked fine since so I have a feeling that's the one going bad.
Yes, R9 would be the high speed fan relay and is the one most likely to be causing your problem. It will stick again.

Time for a new one!

Cheers.
 

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Blah, whata mess that Zetec/SPI fan system is. Low speed relay A and relay B switching fans from parallel to series, humbug!

My 2004 PZEV fan system is more simple. Always in parallel & only 2 speeds. 3 speeds if you count Off as one speed [:)]

Great job on this thread FocusKnot.
 

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Engineers playing around with ideas there I'm sure, and more parts potentially to have to buy? Always a plus for Ford there. As GM former boss Kettering once said.....'simpler systems cost less money, parts that are not there can cause no problems'.................

Lower fan speeds allow the motor to last longer but once you get too slow the motor then proceeds to burn up faster in my view............
 
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