Outatime28

It was hard not to resist making the title of this thread "MOTHERF****** NISSANS F*** MY LIFE DAMNIT." I love my new-to-me '02 six speed SE but so far figuring out the little things has SUCKED. So what happens is on hot days with the climate control on Auto, the fan on 4 (full blast), one of the 15 amp blower motor fuses goes after a couple minutes. I've replaced the blower motor and blower motor resistor to no avail. I did get a used resistor so that is potentially bad as well. What should my next step be? I need some guidance here folks.

TravisCadello

That's Verry Odd. seems the blower motor is shorted out try swapping it again.

Outatime28

Any other suggestions? I don't think it's the blower motor itself, I think it may be a bad ground. I've read that the blower motor resistor is only used for speeds 1-3, and the fourth speed has a ground of its own that bypasses the resistor. If that is true, how do I go about checking the ground?

TravisCadello

You have to look in Repair Manual under eltrical to find diagram. that or find two grounds in clip goin into eltrical clip for blower motor and splice in and add ur own ground.

DennisMik

iTrader: (2)

Manual climate control systems use a blower motor resistor for speeds 1 to 3 and the high speed is directly through the fan speed switch in the dash controls.

On auto climate control systems, things are done differently. There is no blower motor resistor, it's counterpart is the "Fan Control Amplifier". This unit controls all 4 speeds.

The way the blower motor is electrically wired is power starts at the two 15 amp fuses under the hood and goes to the blower motor. The other side of the blower motor goes to the fan control amplifier that acts as the on/off switch and connects the blower motor to ground so that it spins.

When the fan control amplifier goes bad, the vast majority of the time the blower motor will not spin. The other times the fan runs constantly. This is because the fan control amplifier is a transistor that either burns up and opens up like a blown fuse or it shorts out and becomes like a piece of wire.

I have not heard of a fan control amplifier causing the fuses to blow. The blower motor is the part that causes that. Other possibilities for blowing fuses is that you are not using 15 amp fuses (dark blue color), you have defective fuses or the wire from the fuse is shorting out to ground. BTW, is it always the same fuse that blows?

Outatime28

Yeah I think it's always the same fuse that blows, and I always use 15A fuses. I've been through several fuses from different places so the chance of defective fuses are 0. It is auto climate control so I guess I was off there. How likely is it that the brand new blower motor I got from Amazon is defective? I swapped back in the old one because I assumed that it was not the cause once the new one continued to blow the fuse.

DennisMik

iTrader: (2)

While everything I know points at the blower motor, the odds of 2 blower motors doing the same exact thing is rather slim. Especially when you look at how the fuses are wired into the circuit.

Nissan calculated that the blower motor needs to be fused at 30 amps. Instead of using one 30 amp fuse, they used two 15 amp fuses in parallel (side by side). Don't know why. So you start with two separate fuses and run wires from those fuses to the fan. Somewhere in the wire harness, those 2 wires connect together and only one thicker wire goes to the blower motor.

So if the same one fuse keeps blowing, I have to wonder if the wire that comes from that fuse is shorting to ground somewhere before it merges with the other fuse's wire.

That or the other fuse is blown but looks good so that in reality you are running on one fuse. This is a possibility because the blower motor doesn't actually use 30 amps.