A lot of people on here have cooling fans that stop working and cant find the root of the problem. Temp sensor, fan switch, relays, and fuses not being the problem... It seems as tho everyone wires a toggle switch... Is there ANYONE out there that actually found the true problem for this? I have the same problem btw.

 

Well I would imagine that if you have assuredly eliminated all of the parts to which you have listed as not being the cause of your problem then the only two things left would be a worn out fan motor, or heavily corroded wiring that has become so laden with resistance that the fan simply cannot draw enough power to continue running with out over heating the motor and eventually burning the brushes to the commutator. Electric fans draw quite a heavy load and aftermarket fans typically draw even more than stock fans, hence the common neccesity to add a relay and appropriate upgraded wire gauge to ensure the proper amount of amps are supplied to the fan without overloading the fuse panel. A fact that most people over look when installing a replacement fan. The other part of this equation is wether or not the alternator is actually functioning properly and is capable of supplying the electrical system with enough amps to power all of its demands. On import vehicles it is common to see an aftermarket replacement fan eventually cause the alternators internal regulator to fail from the huge kick it recieves when a high amp replacement fan turns on, draws as much as 25 amps for a few minutes, then cuts off.

 

both of my fans still work as i have them setup through toggle switches. When i supply the relays w/ power the fans work

 

Does the vehicle have A/C ? Some times the A/C pressure switch will fail and interfere with the fan relay because the Entire Circuit is not complete. This is usually a four pole relay so it is a bit more complicated to test than a typical three pole relay. It would also appear that at least on the TBI models the oil pressure switch is wired to the same circuit as well.

 

Relays should have a hot control voltage to it when the ignition is on. It is activated by providing a ground. The temp switch and A/C pressure switch will provide this ground. Should be able to ground the wire to temp or A/C switch to a ground and have the fan come on with ign in run.

 

my system works pretty well, being that it's pretty much stock - even with a 195 t-stat. i have a/c in my car, and basically all i have done is put in a lower temp fan switch (200 on / 185 off) and a stewart high flow water pump. other than that, it works as advertised - with the exception that my primary does not like to go off once it comes on, sometimes even a cold day. i think that may be because of the t-stat being a 195. i should probably go to a 180, and i would think that issue would go away. agree? i also have indicator lights on my dash, tho, so i know if the fans are on/off and if they should be in either state. i have never had to put or even thought about manual over-ride switches, and took the ones out that were in my IROC when i bought it.

 

Actually I could be wrong about this but I would suspect the high flow water pump is the reason your fan stays on in opposition to your need for a 180* t-stat. My reasoning is that you are quite likely pumping the coolant thru the radiator to fast for it to be entirely efficient. It's hot going in and still fairly warm coming out of the radiator. Or your fan set up is not pulling/ pushing(whatever your cases may be) a high enough volume of air thru the radiator. Is the fan stock or aftermarket. Not all aftermarket fans are rated the same. You should have a fan that moves a minimum of 2500 cfm and the core needs a full shroud to optimize the draw.

 

If that were the case the water would also be going through the engine too fast to get hot. More likely his thermostat is restricting flow before the fan switch shuts off.

 

According to Haynes the 195* stat is stock, It should close at 185* which is the same heat rating as the fan off temp, I could see how the fan may turn off quicker when its colder out as opposed to when it warms up. I've always been in Houston and here you never have to think about freezing up the motor so 160* is the norm.

 

well the engine cools down to normal temp while the car is moving, but i think it's just warm enough for the fan not to shut off, but not hot enough for the stat to open, either. i've checked it with a laser temp reader, and seems to be normal. kinda hard to shoot a beam where the switch is, but can get close enough with the headers. figured that was the most logical place to try to get a read on it, since it's where the switch is... i figure with a 180 stat that it'd open up and keep the engine cool enough to keep the fan off. when i said the fan doesn't want to shut off, that's on the highway, too - once again in that 185-195 range, i suspect. btw, yes, my fans are stock.

 

i am yet to try to ground the temp switch because my car is in the shop getting new gears installed... but when i jumped the A,B terminals on the ALDL the primary came on as it should