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Cooling fan failure

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spyderdrifter

10+ Year Contributor
5,267
711
Jul 11, 2009
Somewhere in, Colorado
My radiator fans are no longer coming on. The cooling fan for the engine (passenger side) I figured just wasn't cycling on due to engine temp. However after letting the car run for a good 20 minutes, it still doesn't come on like it should. I decided to try to force it on by turning on the A/C fan, and that one is no longer turning on either. I recently replaced my thermostst (with and OEM unit) since the old one failed and wouldn't allow the rad fan to cycle. During that time, which was only a week ago, the A/C fan would turn on when I switched it on. Since I had to drain coolant to swap t-stats, I decided to redo the the rtv on the water necks and t-stat housing since last time I used permatex adhesive by mistake. When I reinstalled the housing and was hooking all the connectors back up, I noticed the harness side connector for the large temp sensor had seperated from the wires. I've reconnected the wires and plugged it in. If this sensor's wires are backwards, will it prevent the rad fan from cycling? Would it affect the A/C fan?

I read in a post a little while ago about the fan switch at the bottom of the radialtor. What does it look like? What is the exact location? I got stock fans with a Mishimoto radiator if that makes a difference. What can I check for the A/C fan operation? I've already checked fuses and relays, and they're fine. I don;t have a multimeter to check other things.
 
The fan switch is under the radiator fan (not ac fan) and it looks like the coolant temp sensor in your lower thermostat housing.
 
Let us know if you can't figure it out and we will try to help you troubleshoot it.

Cheers,

Mike
Mishimoto
 
Still can't figure it out. Whatever sensor the previous help suggested was wrong. There's no sensor on either of my fan shrouds, nor a location for such a sensor. They are stock, and the original shrouds/fans.

Here's a pic of my rad fan. Just pulled it out and as you all can see, there's no sensor or any provisions for a sensor to be mounted.

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The fan switch is under the radiator fan (not ac fan) and it looks like the coolant temp sensor in your lower thermostat housing.

Where's your info coming from? There's no such item on my fan, and it doesn't make sense to be there.
 
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its not on the fans themselves its located on the radatior

Where at on the radiator? Same location that was claimed on the fan? There's still nothing on the radiator. I will have to go to my storage garage to check the factory radiator I still have, but the fans worked just fine a week ago, after having the Mishimoto radiator for a year with no problems.
 
Awesome. I think the problem was the original connector. When I spliced it back on, the de-pinning of the connector didn't go to well, and I had an issue with putting it all the way on. When I finally got it on, I think it pushed one of the pins back. Got a new one on now, and have to wait for my new ignition coil to come in today to start it. Does this affe t the a/c fan too¿
 
Well I got my new coil installed and started my car up. Good news, is that the A/C fan now works again. Bad news is the radiator fan still isn't coming on after the car warms up. Also rather than start a new post, since this is related to the fans, my upper rad hose bloated up this time, and the lower hose still remains cold. I've installed a new OEM thermostat that has 0 miles on it and has only been in the car for maybe 4 days. The lower hose shouldn't be staying cold. When I installed the new t-stat, I also installed what is supposed to be an OEM rad. cap. However, after I removed it about 10 minutes ago, the entire cooling system depressurized and started making the over-flow bottle bubble. That was actually when relieving the cap pressure without fully removing it. I know the right cap is supposed to be rated at 13lbs, which my old one is, and the new one just says 0.9 on the right side (see cap with yellow sticker in pic). I put the old cap back on and the system now lets coolant into the overflow when I squeeze the lower hose. I'm letting the car cool overnight and will restart later today to see if it returns to normal functioning. I don't know how old the hoses are, but I'm sure they'd benifit from being replaced, which I'll do soon. Main issue though is that my rad fan is still not turning on. I replaced the bad connector for the temp sensor and still nothing. I don't know why I'm back to being able to turn on the A/C fan, I haven't changed anything aside from the sensor connector and my ignition coils. Could having the wrong radiator cap keep the rad fan from turning on? With a new t-stat, what could possibly be keeping the lower hose from warming up? Really need some more insight on these problems... :pray:
 

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Forgive me for my ignorance, but is there perhaps a radiator fan control module on the 2Gs? I have a third gen and I have a large module attached to the driver's side radiator fan. When changing out my blowoff valve I must have accidentally disconnected it (had to be already coming loose, not clipped into place) as my car started dumping fuel at a red light when taking it out for a spin and I noticed my coolant temps were around 120*C. Plugged it back in and all was well again.

If you do have one perhaps yours died?
 
My fans are also ECU controlled and there is still a control module which must be functional for both the fans to work. I know you would be able to tell if you had one though as it's a large box attached to the back of the radiator fan. Wish I had more ideas :/
 
Unfortunately at this point you've done all you can as far as replacing items, but you really need a multimeter to see where power is or where it stops so you can go through further deductive reasoning. If you've got a Harbor Freight near you and yesterday's newspaper you can grab one for free.
 
OP did you ever find out what the issue was with the rad fan not coming on? Im having very similar issues with mine as well. I have a multimeter and i'll be checking things also.
 
Well I got tired of troubleshooting and getting no where, so I put all the original parts back on. I tested the old t-stat and it tested good. So old radiator, t-stat, and rad cap went back on and did a coolant flush and proper system burping, and it's been fine ever since. I also replaced the ECT sensor since I was in that area. I still have no clue as to why the A/C fan didn't turn on, but I did manage to get it running before swapping all the parts. I seriously think the problem was that it needed the burping, nothing else made any sense. I tested the fans, the old t-stat, and the old rad cap, and everything was fine. Never got to test the old ECT since it conveniently broke when I was removing it. Luckily I had a spare. So I'd say first and foremost, do a flush and system burp do make sure there's no trapped air. Then if that doesn't solve the issue, you'll have to start spending a little money.

Guess I kinda forgot to keep this updated... :ohdamn:
 
Coolant temperature sensor/sender!!
1998GSX
Stock part # MD182467
My cooling fan stopped turning on, normally it would cycle on when the engine got warm enough. However recently it stopped turning on.
On a side note, I could turn the A/C on from inside the car and the A/C fan would kick on, and with it the cooling fan would be on. But I could not get the cooling fan to operate alone without the A/C.
My salvation came when I went and bought a engine coolant temperature sender from oriellys for 19$ (made by import direct, temperature sender). Install was painless. Fan cycles perfectly now.
 
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