1G Radiator fans wont turn on

[BoostinAWD]

Anyone had this problem before? My car overheats after about an hour and I noticed my radiator fans wont turn on? Is there a fuse for this, I've had bad luck with fuses. Need as much advice as possible. Thanks

kc

 

[Dark_Horse]

Answer taken from: http://members.shaw.ca/costall/1000Q/

My car overheats! Is there a fix?
My car runs hot, but my cooling fan does not come on! Is there a fix?

Yes. Replace your thermostat. 99% of the time a serious overheat is a stuck thermostat. Although you can use a cooler thermostat, this may not be a good idea. See this answer for why.

If this fails to solve the problem, you may be having difficulties with your coolant temperature sensor. This sensor also affects idle, air/fuel mixture, and timing, and failures can generally be detected by the ECU as error code #21. A burned out fan switch or relay may also be the fault.

For racers that run their car at sustained high RPMs, it is possible that their cooling pump may not be operating that well due to cavitation. For these people, an underdrive pulley will spin the cooling pump slower than typical, allowing it to operate properly. This is not a concern for non-racers.

It is also possible for the car to overheat if you blow a coolant or heater hose. This will be obvious, as you will open up the hood to see a cloud of steam and coolant sprayed everywhere. The hoses in most of these cars are getting old - you may want to replace them before this happens.

Failing those solutions, here is a checklist of things you can try to fix your problem. Try the ones at the top of the list first. The correct solution will be different depending on how the car overheats. Problems at low speeds are usually problems with thermostat, fans or switches, or insufficient coolant. Problems at high speed are usually airflow problems caused by front-mount intercooler installations that require upgraded radiators, different thermostats, or ductwork to fix.

Low coolant levels. Top up your overflow bottle. There should always be coolant in the bottle. If your system is perpetually low on coolant, your bottle isn't big enough.
Your overflow bottle is not allowing coolant back in. Check the overflow bottle still has a hose leading to the bottom of the bottle. The system must be able to draw coolant back in.
Flush your radiator. Old coolant (or a clogged radiator) could be the problem.
Try adding some Water Wetter or RMI-25 to aid cooling. Note that some of these products promote corrosion to a small degree.
Your radiator cap might be old, and leaking too easily. Try a 16 lb radiator cap from a Nissan 300Z TT. Watch out - you might blow old heater or coolant hoses with the higher pressure, so be careful, or replace your hoses beforehand.
Your fans might not be running. Replace the fan temperature switch at the bottom of the radiator.
Try a 90/10 to 70/30 water/antifreeze mix. More water leads to more cooling, but easier freezing and more corrosion.
Replace your thermostat.
Try a 180 degC Mitsubishi thermostat. It is part number MD997607.
Try running with no thermostat. If you still overheat, the problem is probably not in your cooling system per se; probably your difficulty is airflow through the radiator.
Wire both fans to run simultaneously. Obviously this only works if you have an secondary (air conditioning) fan to hotwire.
Run both fans permanently. That is, wire them to be always on. Note that the driver's side of the radiator probably doesn't cool as much as passenger side, because of where the radiator inlet and outlet are placed.
Remove the rear hood weatherstripping. Or, shim the rear hood hinges to raise the rear hood edge about 1/4-1/2". This promotes airflow out of the engine bay.
Install better fans. There are "high-performance" models available - get the ones with the best airflow.
Try shrouded fans instead of unshrouded fans. Shrouded fans seem to cool better.
Install some ducting to force incoming air into radiator. This mostly works only if you are having problems only when driving at highway speeds.
Install some high-temperature weatherstripping on top of radiator to try and force more air through it.
Open up front bumper fascia to allow more air flow to radiator.
Replace or upgrade the radiator. Fluidyne and Arizona Performance make upgrade models. You can try to get your radiator cleaned (or "rodded out") if you want to.
Install an external oil cooler to try and lose some heat that way. Leave a gap between the oil cooler and the radiator, if possible.
Wrap the water pipe near the turbo with heat wrap or jet hot/ceramic coat it.
If you have the air conditioning still in, remove the A/C condensor.
Maybe the water pump belt is slipping.
Install a new water pump.
Check your crankshaft pulley has not separated.
Check that your A/C refrigerant level is correct. Only applies if the A/C causes the overheating.
If all else fails, maybe a leaking headgasket is the problem.

 

[Old Mitsu Tech]

I got a headache. Post too long. I'm too tired, but here goes.

If getting hot going down road, possible thermostat or cooling/air restriction to radiator. If hot when sitting still, probably fans not coming on. This is of course assuming nothing has been tampered with or altered from stock.

First, if you have air conditioning, turn it on with the engine idling.

If the fans come on it's likely the cooling fan switch by thermostat housing.

If the fans do not come on with the air conditioner, check for 12 volts to fans. If it's not there, check the relay if it is there it's likely the fan motor. Sometimes you can swap relays in the fuse box to check that venue. Also, if the fans do not come on with the air conditioner, do not leave the AC on as it will build up a very high head pressure very fast. This is only for quick test purposes.

Post what you find. Good Luck

 

[SexperT]

I am too having this problem, i didnt noticed it til it was too late and i blew my HG. I dont have AC so there is no way to check that but here is the thing, switched fuses, and there is power to the Radiator, the fans turn on 1/2 the time. So I turn my key to start the car and it wont turn on the fans, i turn the car off, try again and it will work, turn it off, try again and it wont, and so on... What i was thinking is just connecting it so when i give power to the car the radiator fan turns on automatically all the time. Any advise? thanks