Cooling fan not working

[ESHesse59]

My coolant fan isn't switching on. I can ground out the cooling fan switch and it comes on so I know the fan works. I replaced the switch but even with the new switch I get the same situation. What am I missing here?

[cushman eagle]

Are you letting the engine get hot enough to trigger the switch?
My '99 normally runs with the gauge at the 2nd thick bar,,and, if I am in heavy traffic in hot weather, the gauge will go up 2 more bars,at which time the fan will come on.That will bring the temp down,which shuts the fan off until it gets up to the trigger temp.

[Nails]

Just leaving it idle will usually get it hot enough to trigger the fan.

[Vdriveboater]

Out of curiosity to see if the cooling fan worked, I let my bike idle for awhile after returning from a short ride and with my IR temp gun I saw temps at the back of the cylinders of 240 and 230-235 at the front of the radiator, and the cooling fan did not engage (temp gauge showed close to 1/2 way up the dial). After I took the temps I noticed that the coolant reservoir level went from half full (cold) to almost full, which I've never seen previously after a ride in any ambient temps (maybe 1/2 inch coolant level rise). Another thing I've noticed is that it takes more than 5 miles of riding to get the temp gauge needle to even move, and if the ambient is below 70, it can take 20+ miles to get near the first mark if I'm doing at least 50mph. If I'm in stop and go for a few minutes the gauge does go up, and depending on how long of a ride I'm on, the gauge will slowly drop over 5+ miles when I'm doing 50-60 again. It acts like there is no thermostat, so I'm wondering if a previous owner removed the t-stat because the fan stopped working and they wanted to maximize cooling to avoid overheating.

Can someone give me front of radiator temps at which point your cooling fan turns on? I find it hard to believe that the fan switch is designed to engage at temps above 230F, but I'm no engineer. Regardless I plan to replace the thermostat as a starting point.

[Nails]

Your anecdotes about how long it takes to to get warm doesn't seem out of line to me. I think you're sniffing the wrong hydrant to think that there's something wrong with the thermostat. (I dispute that " It acts like there is no thermostat".) A simpler potential explanation is that the fan or switch isn't working. I suspect the bike is getting hot because the fan isn't coming on, not because of a problem with the thermostat. If the radiator is that hot, the switch or fan itself obviously isn't working. Have you tried getting the fan to run by bypassing the switch. (Note that the fan switch is completely separate from the temp gage sending unit.)

Having said that, there are good reasons (rotten o-rings and hoses) to get into the thermostat housing anyway. This would allow you to see the actual coolant level in the motor -- the reservoir level might not be accurate, such as if the return line is partially blocked. But that would cause overheating very early after starting, so probably irrelevant here.

I added a dash light that comes on with the fan, to monitor whether the fan is coming on at speed (when I couldn't hear it -- I'm half deaf anyway). But honestly not very useful ... yet. (I often ride in the wicked-hot desert.)

[GrandpaDenny]

Nails, your fan comes on at speed sometimes?

[Nails]

Nope. I can confidently say so because of that dash light.
But my "spuds" sure do get fried in triple-digit heat all damn day. I need a fan for that.

[GrandpaDenny]

I've thought about putting a small fan on Gertrude. Sitting in traffic gets hot. Me, not the bike. Well, she does, too, but she's got a fan to cool her right back down.

[Vdriveboater]

Tonight I accessed the coolant temp sensor/switch, pulled apart the bullet terminal connector, and per a post I read on this site, used a jumper wire with alligator clips attached to the wire going to the fan and touched the other end to ground. With the bike not running and key in full right position and with the bike running, I was unable to get the fan to turn, even after trying multiple ground sources and re-connecting the alligator clip several times to the female bullet terminal on the wire to the fan. I verified that the 10A fuse for the fan is good. Looking from the side, the entire fan assembly looks quite clean and undamaged, but that is no indication of its electrical status. I did notice a wire going to the fan that's attached to a bolt (ground) at the upper left right side of the radiator. If that's the radiator motor ground, what's the purpose of the sensor/switch grounding? Also, is there not a relay that switches power to that motor? Any other methods of testing the fan motor would be appreciated.

[GrandpaDenny]

Interesting. The "far right" position on the ignition is the "park" position - engine off, headlight off, taillights on I believe, and hazard flashers operational. However, the fan will operate regardless of ignition key position, whether the engine is running or not, whether the ignition is on or not.

[Vdriveboater]

By far right I mean full clockwise (left being counter-clockwise).

[GrandpaDenny]

By far right I mean full clockwise (left being counter-clockwise).

Right. Key positions from the left are LOCK, OFF, ON, PARK. In the ON position the key is straight up. If you're going all the way to the right, you're going to the PARK position where nothing works except the taillights and four-way flashers. Oh, and the cooling fan - it works in any key position, whether the ignition is on or not, whether the bike is running or not. So you should always have power to the fan relay.

[triton28]

Vdrive;
yes there is a relay for the fan. It is the only relay with a solid Yellow as one of the four wires going to/from it.

[Vdriveboater]

By far right I mean full clockwise (left being counter-clockwise).

Right. Key positions from the left are LOCK, OFF, ON, PARK. In the ON position the key is straight up. If you're going all the way to the right, you're going to the PARK position where nothing works except the taillights and four-way flashers. Oh, and the cooling fan - it works in any key position, whether the ignition is on or not, whether the bike is running or not. So you should always have power to the fan relay.

Thanks for the info Denny, I didn't know there was a key position to the right of "on". I tried to turn it past "on" once but apparently I didn't use enough force. I have thought it seemed odd that the hazard flashers would only work when the ignition was "on", but it makes total sense to have another position for power to go only to the tail light and hazards.

[Vdriveboater]

Vdrive;
yes there is a relay for the fan. It is the only relay with a solid Yellow as one of the four wires going to/from it.

Thanks for the info Triton . I just received a used cooling fan assembly from fleabay, and I just tested it and it works. I also received a new radiator coolant sensor/switch and will test it shortly (with a heat gun) to determine at what temp it closes and grounds the circuit to turn on the fan (which I will share). In the service manual I downloaded from the website there is no mention of the temp at which the cooling fan turns on. As I posted previously, I tried grounding the sensor wire but the fan didn't work, so it's got to either be the fan motor itself or the relay, and it looks like I'll have to remove the entire left side fairing pieces to get to that relay/connector. The good news is that, now that I know how to test the fan from the connector terminals (actually just putting B+ to the blue wire terminal), I can test it while it's still attached to the bike w/o having to remove it. If the fan works in the test, the issue almost has to be with the relay.

[Nails]

After the first dozen or two times, removing the fairing will be a non-issue.
Note that all the relays are identical (you can swap them to test), and Dollar-for-dollar has cheap sources for them.

[Edit: but I have to ask: if you found the problem, and now it works ... why are you still fixing it?]

[GrandpaDenny]

Thanks for the info Denny, I didn't know there was a key position to the right of "on". I tried to turn it past "on" once but apparently I didn't use enough force. I have thought it seemed odd that the hazard flashers would only work when the ignition was "on", but it makes total sense to have another position for power to go only to the tail light and hazards.

You might have to push in on the key a little. It doesn't take much force. The lettering on my ignition switch are long worn off; if I hadn't owned another bike years ago I would never have thought to test to see if it had a "park" position. I have an e-version of the owners manual, too, but I don't think I actually read that part LOL. You know, the controls and instrumentation parts I think, like "yeah, yeah, I know all that stuff".

[Vdriveboater]

Thanks for the info Denny, I didn't know there was a key position to the right of "on". I tried to turn it past "on" once but apparently I didn't use enough force. I have thought it seemed odd that the hazard flashers would only work when the ignition was "on", but it makes total sense to have another position for power to go only to the tail light and hazards.

You might have to push in on the key a little. It doesn't take much force. The lettering on my ignition switch are long worn off; if I hadn't owned another bike years ago I would never have thought to test to see if it had a "park" position. I have an e-version of the owners manual, too, but I don't think I actually read that part LOL. You know, the controls and instrumentation parts I think, like "yeah, yeah, I know all that stuff".

The first time I tried it (knowing that position existed) it was easy peasy -- thanks again!

[Vdriveboater]

So here's the latest report. In order to disassemble the thermostat housing to access the thermostat, I had to remove the radiator, which took some time but got it done. I discovered that the t-stat itself was damaged, in that the top piece (like a bridge) that's welded on two opposing sides was laying by itself, meaning the welds failed. I'm not sure what impact that had on the actual t-stat operation? I then dunked the t-stat in an electric teapot I keep in the garage, and even after 2 minutes of hard boiling, the t-stat didn't open. I then dunked the fleabay replacement t-stat (w/o the bottom piece that the original had) into the teapot and it started opening well before it started boiling. I'm thinking that I was very fortunate that I didn't have any overheating issues since I've had the bike (a few months). I lightly cleaned the mating surfaces of the t-stat housing, put it back together with the two bolts, and after a full temp cycle (fast idle for 10+ minutes) it seems to be functioning and no leaks detected. I watched the temp gauge (sensor located at the bottom of the t-stat housing) rise and then fall, which I assume was the t-stat opening, and then it rose again and leveled out. I had not seen the gauge operate this way before, probably an indicator that the old t-stat failed in the closed position. It will be interesting to see how the temperature looks like once I get everything back together and go for a 20+ mile ride.

The second issue (fan motor) is a head scratcher. I was unable to located the relay, or at least identify it. By applying 12V to the blue wire terminal in the 3-way connector that goes to the cooling fan, I was only able to get the fan moving only if I ran a jumper wire from the green wire ring terminal (that's secured to the upper right side of the radiator) to a good ground. Which means that, although the OEM bolt and ring terminal are clean, there is not sufficient ground there to operate the fan motor. So I will make a permanent jumper wire from that ring terminal to ground. The bike came with a small switch installed on the lid of the left side fairing storage compartment lid for LED mood lights (which I removed), and I test ran a wire from the battery to that switch and another wire from the switch to the blue terminal for the cooling fan, and it worked perfectly. So just like a driver has the choice of when to shift a manual transmission, I'll have the choice of when to turn the fan on and off. I live in a semi-rural area in MI, so the only time I would need the fan is if I get caught in stop and go traffic (accident or construction) which would be very rare. I tried using the fan last night and it caused the temp gauge to drop after a couple minutes, and I verified this with my IR temp gun. Frankly I feel more comfortable being in control of the cooling fan as opposed to counting on the 30 year old bike's electricals to all function as they should. The last thing I want is to be sitting on the shoulder of a road in traffic with an overheated bike.

A couple of pieces of info I'd like to add for everyone's benefit. The thermostat housing ID has a pretty large "opening" at the OD of where the t-stat sits (a sort of groove in the casting), which allows a fair amount of warm coolant to circulate (along with the tiny weep hole in the t-stat) before the t-stat opens, and I noticed the radiator start warming up long before the t-stat opened. I'd never seen a design like this on a car, but maybe it's something common on water cooled motorcycles?

The other item is that the radiator cooling fan pulls about 4.6 amps at 13 volts. I added a 10amp fuse to my manual fan switch as protection.

[Stew]

My 03 is set up with a toggle as well. I suspect that the fan switch on the rad went out and my late uncle just ran the fan with a toggle. Seems to work fine though. I live in the country and am rarely in congested traffic with lots of stop and go so I hardly ever have to flip the switch to turn the fan on. In the last 5000 km's I think I've only had to kick it on 2 or 3 times for a couple of minutes each.