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Radiator fan not coming on.

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BenKenobi

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Discussion starter · #1 ·
I just picked up a 2012 Odyssey EX last Saturday and I noticed yesterday that the cooling fan stopped working. I do have a 90 day / 4000 mile warranty, but the dealership is 2 1/2 hours away in Mobile. So I'd like to troubleshoot this and fix it if it's a simple/cheap problem. If I determine it's out of my wheelhouse or goes beyond my troubleshooting abilities, then it's roadtrip time!

So far, I've determined that:

* The fan is not getting voltage
* The main fan relay is working.
* The main fan fuse is intact and has voltage.

I plan to look up how to test to see if the relay is getting voltage and test that as well. Is there anything else I'm missing?

Thanks!
 
#2 ·
First thing to do is be very specific about the symptoms. There are two fans. Driver's side is the "radiator fan" and the passenger side is the "condenser fan." Are they both not working or does one work and the other not work? Also, do the fans work if you turn on the AC?

Second thing to do, once we get exact symptoms noted, is to get a wiring diagram:

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=75611

There are two 30A fuses, two fans, two fan speeds, three relays and the PCM. Where we go on the diagram depends on the exact symptoms. I've been through this before so once you can post all the details we should be able to get you headed in the right direction.
 
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Discussion starter · #3 · (Edited)
It is indeed the radiator (driver's side) fan. It will not come on under any conditions. A/C on or off, I've monitored coolant temps while probing the plug that goes into the fan up to 210 degrees and no voltage.

That said, you mention two fan speeds (I saw this somewhere else too) and it occurs to me that the two wires going into that plug may not be positive and ground but high speed and low speed with it being grounded somewhere I can't see? Maybe I should try probing each one while touching the body for ground?

Thanks!
 
#4 · (Edited)
Well, I screwed up in my post above. That's the wrong diagram. This is the correct diagram:

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=890024

The two wires going into the radiator fan (left side) should be a power feed and a ground. Have you checked the ground (black wire) to make sure it's good?

In low speed the fans run in series, powered by the condenser fan fuse and relay. In high speed the fans run independently, which each relay and fuse powering its associated fan. The PCM controls whether they run in high or low with separate high and low outputs grounding either the condenser fan relay or the radiator fan relay depending on which one is being called for.

Which relay did you test? Also, does the condenser fan run on both high and low speed? They both should run on low when the temp reaches around 194F and they should both go to high when the temp reaches 205F or the AC high side system pressure reaches 221psi (basically with AC on.)
 
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#5 · (Edited)
Here is what I would do if it were me testing this. I'd start the vehicle and turn on the AC. That should command high speed on both fans.

Then I'd go to the Radiator Fan Relay in the underhood fuse relay box and remove the relay. There are three different relays so make sure it's the Radiator Fan Relay. Does the relay click when you unplug it and plug it back in? That will tell you if the PCM is commanding the relay to close. It won't necessarily tell you if the relay is sending power to the fan, though, but it rules out the control side of the relay. Then, pull the relay out just enough so that it's still making contact in the terminals but out enough that you can put a test light on the #2 pin which is the power feed to the fan. If you have power on that feed then you know the problem is between the relay and the fan.

I'm just throwing out a theory here based on the fact that neither low nor high speed works...It appears that the power feed to the fan branches off of a splice in the underhood fuse/relay box. If there were to be a problem with the splice in the fuse/relay box that disconnected the power feed to the fan motor that would explain why neither low nor high speed would work. My suspicion is that either that splice/connection is bad or the ground, G201, is bad.

If this is where the problem lies then low speed will not work on the condenser fan, either. It's important to know if the condenser fans works on low speed above 194F (approx.)

A test light is your best friend in this type of troubleshooting. You can easily check a ground by connecting the alligator clip to battery positive and touching the ground wire. You can check a power feed by connecting the clip to battery negative and touching a power feed. Once you understand how the circuit works it should take only a few minutes to find the problem.
 
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Discussion starter · #6 ·
I "tested" (and I mean that loosely) the "MAIN FAN" relay by swapping it with the wiper relay. Those were the only two that were the same type. The wipers still worked after switching them, so I ruled that one out. There's another one called "SUB FAN" I'd assumed was for the condenser fan, but I'll try what you suggested (test light under the relay) and poke around a little more with what you've given me here.

It probably wouldn't hurt to run direct power to the fan just to make sure it's actually working and I wasn't testing things incorrectly.

One thing I noticed a couple days before the fan stopped working was that after shutting the van off, one (or both?) of the fans would keep running. Since I'm new to the vehicle (and it's the newest vehicle I've ever owned) I figured it was just normal behavior. I had a '90 Prelude that would do the same thing.
 
#7 ·
It can't hurt to try jumping power to the blue wire on the fan motor and see if it runs. However, you already said it's not getting power on the blue wire so you already know there is another problem. You just need to figure out where the problem is.

The fans shouldn't run when the engine is off.

To be clear on the relays I've posted a diagram. Make sure you're working with the proper relays.

15 - Radiator fan relay
6 - Fan Control Relay (this is a 5 pin relay instead of a 4 pin relay)
13 - Condenser fan relay

The 30A fuses for the radiator fan and condenser fan are directly above their respective relays.
 
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#8 ·
It's really as simple as this. Verify the ground is good on the black wire to the fan. Use a test light connected to battery positive and check the black wire to the fan. If the light lights up then your ground is good. That leaves only the power feed--blue wire. The blue wire gets power either from the condenser fan relay, through the condenser fan motor (wired in series) in low speed or the radiator fan relay in high speed. If neither fans work then pick one that's easiest to diagnose and track where the power is being lost. That's the test scenario I described above with the high speed fan and testing with the car running and AC on. Find out where the high speed circuit is losing power and you'll probably solve both the high AND low speed issue. If fixing the high speed doesn't fix the low speed, then work the low speed circuit the same way. To me, unless there is more than one problem, the only way BOTH high and low speeds can be inop is if something common between them is bad and that's why I suspect either the splice in the fuse box or the ground G201 but it's only a theory and needs to be tested to know for sure. If G201 is the problem then the condenser fan won't run on low speed either and you haven't said whether that works or not.
 
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#10 ·
To be clear, you're saying the condenser fan works on low speed when the coolant temp reaches roughly 195F but the radiator fan doesn't? When the coolant reaches 195F BOTH fans should run on low speed.
 
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#12 ·
191145 said:
Is the car getting hot? Any symptoms of overheating? Or is this approach too simple for you?
Click to expand...
At this point it doesn't matter. The radiator fan doesn't turn on with the AC or with high coolant temp. That's the current problem. Overheating, if occurring, would just be a side effect of that.
 
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Discussion starter · #13 ·
I just popped on real quick. I'm about to go get a probe light to check everything, but my wife just got home and said that "a couple times I turned it off, but the engine kept running" (turns out she meant the fan/fans) -- so that's interesting. Thought I'd leave that to brew here for a bit.

To answer the questions above:

To be clear, you're saying the condenser fan works on low speed when the coolant temp reaches roughly 195F but the radiator fan doesn't? When the coolant reaches 195F BOTH fans should run on low speed.
Click to expand...
Correct. The condenser fan runs when it should, turns off when it should. I don't know if one or both fans is running after the van shuts off though.

Is the car getting hot? Any symptoms of overheating? Or is this approach too simple for you?
Click to expand...
I'm not sure what your last question is implying ... but I'm pretty sure I said "I've monitored coolant temps while probing the plug that goes into the fan up to 210 degrees and no voltage." so yes, car gets hot. It will get up to at least 230 in traffic when not moving. I didn't let it go past that because I saw the gauge was high and cut on my heater to keep the temp down.

Sorry if I didn't specifically say that the van was overheating / running hot (although my definition of overheating is anything outside of normal operation -- whereas maybe yours is hitting the red mark on the gauge? I don't know.), but it was definitely implied above that the coolant temperature was going above the point at which the radiator fan should be on.

...but like John said, that's not really relevant at this point. I'm off to the store. Will report back. Thanks!
 
#14 ·
You're still being unclear about the condenser fan. There are two speeds. With the AC off, when the coolant temp reaches about 194-195F both fans should run on low speed, cool the temps down a bit and then shut off and this cycle should repeat. That is proper operation of low speed. This speed is barely audible but just enough to pull some air through the radiator. When you turn on the AC both fans should run on high speed.

Are you seeing BOTH speeds on the condenser fan? If the coolant temp gets to 195F or higher, with AC off, and you still have NO cooling fans running then the condenser fan is NOT running on low either. Maybe it works on high when you turn on the AC but we need to know if it's working on low speed. This is an important detail to know when troubleshooting this.

The fans running after the vehicle is shut off indicates one of two things. Either the engine is so hot that the PCM is commanding the fans to high speed to cool the engine down after you shut it off. I'm not 100% sure if the PCM has that programmed into it or not. I've never seen mine run after shutting down but I've never had any overheating issues, either that would command that. If your engine is getting hot while driving it and going up into the 205F or higher range then high speed might be commanded after shutdown. I do know that with the engine running, and when the coolant temp reaches 205F, then BOTH fans turn on to high speed, regardless of AC on or off, so knowing whether both fans are running, or only one is running, and which one, is an important detail.

The other thing that would cause the fans to run after shutting the engine off would be sticking relays. The load side of the relays has a "hot-all-the-time" power feed so if the relay sticks on then the fans will run until the relay unsticks. For high speed, both fans use their own fuse and relay so if both fans are running then I'd suspect the PCM is commanding them on, since two failures at the same time is unlikely. If only one fan is running then either one is not working and the PCM is commanding them on, or one of them has a faulty relay. Again, knowing which fan is running after shut down is vital.
 
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Discussion starter · #15 ·
Sorry about that... I'll check to be 100% certain, but I'm pretty sure with the A/C off, the condenser fan was not turning on at that temperature. I didn't look specifically for that, but was trying to get the van to that temperature to see what would happen and the condenser fan didn't come on until I turned the A/C on. I didn't notice a change in condenser fan speed at any point.

I was thinking the same thing though as soon as she told me that. Sticking relay. If I can get it locally, maybe I'll pick one up while I'm out for fun.
 
#16 ·
So, if the low speed fan is not working on either fan then that is a very important troubleshooting detail. Are you able to follow the wiring diagram in post number 4 above? I'm pretty sure I know where the problem lies. If you can't follow it and it's too complicated just skip to my last paragraph where I tell you where I think the problem is.

If the condenser fan works on high but doesn't work on low then that means the AC condenser fan relay, fuse, and the "fan control relay" are working because the ground for high speed on the AC condenser fan is made at pin number 2 in the fan control relay. That means the PCM is commanding the relay and the relay is moving to connect pin 1 to pin 2 in the fan control relay. We've ruled out a good portion of the circuit.

However, we know that the high speed works but low speed doesn't. The only part of the circuit left for low speed is between pin 4 of the fan control relay and the radiator fan motor. The ground for low speed fain is made through the radiator fan motor to G201. So, the problem could be the fan control relay not making contact between pins 1 and 4 when it's not being triggered by the PCM. The only problem with that theory is that it wouldn't explain why the radiator fan won't turn on to high speed when commanded since that uses a different circuit.

Since low speed doesn't work on either fan, and high speed doesn't work on the radiator fan, that makes me pretty certain it's a problem between the radiator fan motor ground, G201, and the underhood fuse box, or internally in the underhood fuse box where the splice is made to go to the fan control relay and the radiator fan relay (see the circled area in the attachment.) I don't think this is a relay problem. I think there is either a broken wire somewhere on the blue wire between the connector at the fan and the fuse box, or the ground G201 is bad, or the radiator fan motor itself is bad. You mentioned that the blue wire going to the fan wasn't getting power so that makes me suspect a wiring problem but if there is, indeed, power on that wire then either the fan is bad or the ground at G201 is bad. You'd need to check for power on that wire when the fan is commanded on, i.e. when AC is on.
 

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#17 ·
Additionally, I think the fans coming on after shutdown is probably due to overheating, caused by the inoperative cooling fans, and is something the PCM is doing to cool down the engine. Again, I don't think it's a relay problem.

The caveat here is that I'm just going on what you tell me and I don't have the vehicle in front of me to verify anything.
 
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Discussion starter · #18 ·
Problem solved... I'm a doofus.

I had a choice to make. I could either pretend this never happened, and never come back here again ... or I could face the music and admit my blunder in the hopes that someone else would find this thread and learn from my mistakes.

I went to AutoZone to see if they had the relay, but decided to try one last thing before going in and swapped around two identical relays to see if they problem moved with it... and it didn't. So I decided to take one last look at the two 30A fuses related to the fans... and that was it. A $5 fuse.

In my (weak) defense, it was barely noticeable that it was blown.

So, please, have a good laugh at my expense. Thanks for the responses and patience though, I did learn some useful stuff.
 
#19 · (Edited)
No, I'm glad you posted that. Which fuse was it? Was it the condenser fan fuse or the radiator fan fuse?

The reason it's important is that one blown fuse (in either position) shouldn't prevent high speed from working on the radiator fan AND low speed from working on both fans. Also, it's important to take a look at possibilities of why a 30A fuse blew.

Do you have both low speed AND high speed fans now? To test low speed, let the vehicle warm up with the AC off and see if both fans turn on to low at 194F. Then turn on AC for high speed fans.
 
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#20 ·
I had the radiator fan fuse blow on mine but the symptoms were low speed fans worked fine but when high speed was called for the radiator fan didn't work. My attention was drawn to it because the AC was warm at stop lights and idle and worked fine when driving down the road. I found the fan not running on high. I replaced the fuse and it's been fine ever since. My concern has been what caused the 30A fuse to blow. I checked the amp draw of the fan motor and it was fine. The only way for that fuse to blow is if the motor is shorting out or drawing high current. I haven't scoped the fan, which is on my list, but it's been fine ever since.
 
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