Alright so my car has been slightly overheating lately. It wouldn't happen on the highway but would in traffic with the A/C on. With the A/C off it doesn't overheat. I did some diagnosing and noticed that the left fan (closest to the battery) doesn't come on as it should.

Checked the 15A fuse for it and it was fine. Was going to start swapping relays when I noticed that the big 40A fuse for the fan was blown. Swapped one in from the power windows and the fan started working so I bought a new one and threw it in. Drove the car and it was fine until it popped again. Think it's a bad relay or fan motor?

Cliff notes: Car: '03 with manual climate control; keeps overheating slightly in traffic with the A/C on because fan closest to battery isn't coming on. Found burnt 40A fuse, replaced it, popped again and is slightly overheating again.

 

Anyone?

 

I just recently developed the same problem with my car. The fan tries to spin, but it doesn't unless I kick it over with my finger, then it spins slow and stops. I unplugged that side of the fan to prevent anything from burning out. I have a new replacement fan assembly on order and i'm going to have it replaced next week along with a leaking radiator when I have my lower radiator support replaced due to rust damage.

Electric motors like anything else have a life span. They wear out and quit as a starter or alternator wears out and quits.

 

I have a feeling it might be the motor but I want to make sure before I go spending the money on the new one.

 

Understood. I've had electric motors used in other applications fail on me before, so i'm confident about replacing my radiator fan assembly.

 

I'm not worried about replacing it, just don't want to waste my money if I do replace it and the problem persists

 

Remove it and test it with a multimeter.

 

The fan blew a 40 amp fuse? I'm surprised it didn't melt down.

 

This.

 

40 amps??? The 3 ton central air unit in my g/f's house isn't even on a 40 amp circuit... I believe it's 30 but it draws somewhere around 10-15 amps. That little radiator fan motor should have burst into flames before it blew a 40 amp fuse...

 

But the fan is only running at ~13v

The AC is using ~220v

Even so, 500 watts in a little fan motor like that should equal some sort of destruction lol.

Maybe it's some kind small/intermittent short, although, that doesn't really make sense. If the coils are shorting, then they should have already melted together the 1st time haha.

 

That's what's strange. When I popped the new fuse in, it worked just fine for almost an hour before popping again

 

The watt/volt/amp thing is a bit confusing to me. My grandfather was an electrician and he tried explaining it to me a few times without much success.

 

A 40 amp fuse is what Nissan recommends for the radiator fan. For what it is worth, you have to remember that the fan motor is 2 speed. It is 2 motors in one case with 2 sets of brushes and 2 sets of windings. What is probably happening to the op's motor is that the armature bushings (cheap azz motor, no bearings) have run dry and are binding, causing the motor to pull more current. Motor heats up, metal armature and metal bushings expand, bind more, pull more current and POP goes the fuse. If the op goes and spins both fan motors by hand, I bet the bad motor is harder to turn.

In the world of electricity, the amount of electricity used is measured in watts. To get a rough but fairly accurate wattage rating, multiply voltage by amperage. So our radiator fan motor is 12 volts times 40 amps or 480 watts.

My 3 ton a/c on my house is fused (circuit breakered) at 80 amps (dual 40's) on 220 volts. 220 times 80 is 17600 watts. This is almost 37 times more power than the radiator fan.

 

This is at the maximum, right? Because the fuse is 40 amps doesn't mean it's drawing that much, correct? If it did, it would pop or be very close to doing that. Probably drawing 30ish on the high speed?

 

Usually fuses are twice the normal running current. I have never been curious enough to measure the amperage, but you are definitey correct that the motor does not normally draw 40 amps. I bet that 30 amps is probably on the high side.

Another point on the house a/c is that the circuit breakers are running 3 motors. The a/c compressor, the small condensor coil cooling fan that is in the compressor case and the fan motor that blows the air throught the house.

 

I'll see if you are correct if I get a chance today.

 

That makes sense.

 

When I was having the estimate written up at the body shop for my rust repair, the guy was looking up radiator fan motors. He couldn't find anything aftermarket, only OEM from Nissan. The fan motor itself cost more than buying an aftermarket OEM direct replacement radiator fan assembly.

 

iirc watts & amps are the same ( measure of current )


should be volts/amps/resistance


think of a wire like a garden hose ..the water is volts, the amount of pressure the water pushes is amperes and the diameter of the hose is resistance

hope that helps

 

No, this is not correct. If we use the water analogy (and be flamed by the die-hard electronics engineers) volts is like water pressure, the force that will move the electrons. Amperage (or current) is how fast the electricity is moving. Watts is the amount of electricity that has been moved

 

They aren't. Watts is a measurement of electrical power. Watts = amps multiplied by volts. If you increase either voltage or amperage you would get more power (more watts). To try and explain it with the water analogy.. it would be like how much force you're being hit with by the hose. If you set the hose up to hit a waterwheel then the amount of power being generated by the water wheel would be your watts.

 

So what was the outcome? Bad fan motor?

 

Not sure yet It's been cool enough that I haven't had to use the A/C lol

 

I would bet $100 the motor is bad and is heating up. If you want to run an experiment then put in a new fuse. Run the fan for awhile and then CAREFULLY feel it. I guarantee you that it is about 300 degrees. Of course this is dangerous and your motor will blow eventually but it will surely let you know the armature bushings are bad. It happen. MY fans don't spin freely like brand new fans anymore either so I will have to replace mine as well. Mishimoto makes some quality fans FWIW

 

Probably a bad fan motor. Just get 2 aftermarket slim fans and wire them up to turn on when engine temp reaches a certain degree that the regular fans turn on. I have 2 12" slim fans that work great. May be cheaper than OEM replacement......OEM (Nissan) robs you. I would NOT play with anything that has to do with engine cooling. Overheating the engine will eventually destroy it. I would just get rid of the OEM shroud with BOTH fans and replace with 2 high speed slim fans.

 

Hmm.. That's an interesting idea. Would they wire up like stock? Got any links to what you're running?

 

Well you can just go on eBAY and get any decent slim fan. As far as wiring I believe that you want to wire into the wire that turns the fan on based on temperature. There is one that turns fans on when A/C is on and one that turns fans on based on temperature. You can just baypass the wire when A/C is on and wire into the one for temp that way the fans will always come on based on temperature whether A/C is on or not.

 

Would that be the better way to go?

Anyone else have input on original wiring vs. this?

 

Thats how my slim fans are wired and I haven't had any problems.

 

Op you could also just have both slim fans and just bypass the harness connectors and splice them in as if they were OEM fans so one will work with engine temp and one with a/c kind of like OEM would but with the slim fans .... Just my two cents ...

 

I have mine wired so BOTH fans come on for engine temps regardless if A/C is on or not.

 

Hmm.. I gotta look into this some more. No rush. The car only slightly overheats in traffic with the A/C on. I haven't had to use the A/C in a while due to pleasant temps.

 

An entire radiator fan assembly - both fans and housing, plug and play, can be had for less than $100. Install is a piece of cake. Should be an easy fix. Definitely not 30 posts in a thread worthy.

 

Link?

 

http://www.ebay.com/itm/ALUMINUM-SLI...ht_3940wt_1348

you need to ensure the wiring the fans comes with is correct though to make sure you are not a wire short as some fans are. You can do what Rammas suggested but I like to have them function the same as stock fans so they come on with AC and via temperature. Ask them for a picture of the wiring harness. I believe our fans are 4 wire but I could be mistaken and they are 3. I am not near my car to check ATM. This fan shroud is aluminum as well and the bolt holes wont break if you upgrade your radiator to an all aluminum down the road.

personally I would get these:

http://www.mishimoto.com/mishimoto-fans.html

but obviously they are more expensive

 

Hey if its that cheap then I'd go this route. I didn't know they were that cheap. Im thinking Nissan "STEALERSHIP" prices.

 

My price was based on RockAuto. I'd imagine RockAuto's offering is plug and play harness.

 

I had a new radiator installed when I had my lower rad support replaced (it was leaking) and I also got a new fan assembly since the driver's side fan quit. It's direct replacement. Unplug and remove the old one, install and plug in the new one.

I don't recall which one the body shop ordered (brand) but it was a little over $100 dollars. It looks identical to the old factory one.