erictown

Maxima 2000 SE.

might have a problem with blower motor relay. Now Haynes manual just points out there are ignition relay and blower motor relay at a same block, I found a blue one beside fuses box and a black one behind dash board, which one is ?

the problem is, my 2x15A fuses keep blowing out. According to the diagram below, if I'm not wrong(not a physics guy), only a short relay could burn 2 fuses at a same time, right?

OK, to make things even more confusing, my mechanic buddy suggested me to switch those two 15A fuses to 20A. I did it and my blower motor still get stopped after on about 5 mins. This time the two 20A fuses are still good, only I don't even know this time what in the circuit get burnt off.

I think it should be the relay, so please help me to find it. Thanks in advance.

rebelhell

iTrader: (1)

Looks like it's on the back of the Junction Box

erictown

Thanks, but I can see the fuse box but where is this junction box ?

rebelhell

iTrader: (1)

I believe you're looking at it. The picture shows front and back of the fuse box (or junction block). The blower relay is on the backside, opposite the fuses.

DennisMik

iTrader: (2)

The 2 fuses are wired in parallel, meaning that instead of using 1 - 30 amp fuse and thick wire, Nissan used 2 - 15 amp fuses side-by-side and thinner wire. It is extrermely, highly unlikely that the relay is causing the fuses to blow. While anything is possible, you probably have a 1 in a million chance that it is the relay causing the fuses to blow.

Using fuses of a higher amperage than the circuit was designed for is a mechanic's cash cow. If a fuse is blowing, you have a problem. Using a higher amp fuse does not fix the problem. At best the fuses blow. At worst, the fuses don't blow and your wire harness burns up. Your mechanic is an a$$hole.

Back to your problem. Your blower motor is bad. Probably the brushes are worn out and the wires they used to connect to are flapping around inside the motor and shorting out.

Oh and FYI, the blower motor relay is to the right of the blower motor, mounted in the wall of the car body.

erictown

As i said, I'm not a physics guy, but according to the circuit diagram, if there is a short at motor, resistor or control panel it should only burn the left fuse which is on the circuit, but how did the right fuse get burnt too? It is not even connected to the motor.

Damn it! I get really confused now. You are right man, i checked the relay this morning , it's good, so now what!

DennisMik

iTrader: (2)

Part of your problem is that you are taking that diagram as the gospel truth. Unfortunately it is a theory of operation diagram, not a how the car is constructed diagram. The fuse that it shows on the left side is really 2 fuses, the ones under the hood labeled RAD FAN 1 and RAD FAN 2 (and these are the ones that are blowing - right?). The fuse on the right is the fuse labeled IGN SW. The IGNition SWitch fuse powers a lot of things. If this fuse blows, the car won't run and at least half of the things won't work.

I don't know where that diagram you posted came from. It appears to be a Nissan diagram for a car with auto climate control. Here is a diagram that should be less confusing for you, but this one does not show the relay.



I'm still sticking with what I said in my other post - your blower motor is bad.

erictown

Now I get really bent. Today I went to a car graveyard and got a new pair, well, used ones of course, of blower motor and resistor(amp), I put them on, changed those 20A fuses back to designed 15A fuses. They runs pretty nice.

But not for long

On my way back home, on highway, I found blower motor stopped working again. only this time, those 2 15A fuses didn't get burnt!

So now, I am so frastruated, apperantly the problem is not from motor and resistor, and this time even fuses are good. where the hell get burnt off? and what exactly cause this problem?

DennisMik

iTrader: (2)

A bad blower motor!

erictown

Don't you see it? I have already replaced with another motor, but it still doesn't work. Must be somewhere else get short.

erictown

I'm running out of choices, damn it! have to go see a specialist of auto electric.

I wonder if it is the climate control unit makes the mess or a short in harness? GEE! wonder how much they are going to charge me to open everything......

erictown

OK, just for updates: today i went to an Auto Electric shop, they found out my new resistor was burnt as well. they didn't explained why those previous burnt happened and only for finding out a burnt resistor, they charged me 98 dollars. crazy world, eh?

why this new one get burnt? they said maybe I let it dangled outside thus it doesn't get ventilation to cool down. OK, i went back to car graveyard and get another resistor from a 01 Maxima, installed it into the slot (which actually located inside the housing beside the heater fan). I don't want to go back to that electric shop any more, it is way too expensive. but I'm still at a loose of the exact reason of these blowing outs ( fuses, resistors).

DennisMik

iTrader: (2)

The resistor gets very hot when it is being used. It is mounted in the air stream from the blower motor for cooling. If the blower motor isn't spinning, the resistor will burn up.

Remove your blower motor and test it on the battery to see if it spins.

erictown

DennisMik, I think you are right! I put on another resistor and installed it in place where it can get ventilation to cool it down, everything goes normal so far.

So what happened before, I was trying to sort it through, first it was a bad blower motor which cause the frequently burnt fuses, then I replaced both the blower motor and resistor. But I hung the resistor outside the slot it should be installed in. Now this time, it is the resistor gets burnt because of heat. These happens one after another gets me frustrated.

Now the blowing system works just fine. Thank you man, you are the first guy who point out those burnt fuses were a result of a bad motor, only I messed thing up.