Gemini67

Hi all,

I need to replace the blower motor in my 2003 Max with Auto HVAC - I bought a replacement unit but it only has two wires hanging from it. So now I have to hardwire the new fan motor to the connector - question is - how can I tell the positive wire from the negative wire on the wiring harness. It's marked on the motor but I don't know which one is which on the wiring harness.

**** UPDATE - There is a blue wire with a white stripe and white wire with a blue stripe on the wiring harness ****

Thanks,

PJ

DennisMik

iTrader: (2)

The white/blue stripe wire is the 12 volt wire.

The blue/white stripe wire is the ground via the fan control amplifier.

oldngivout

iTrader: (8)

My advice - return it and get the motor at the Nissan dealer. The aftermarket units I have installed from the parts store are terribly noisy.

Gemini67

Thanks Dennis.

I tried hooking up the fan temporarily according to your wiring and the fan moves slightly when I turn the ignition on - but it won't turn - even on the highest speed.

I hooked up the motor to a battery charger and it runs fine so I know the motor is good.

My next guess is that it's the resisitor - but I thought that the resistor would failover to the highest speed if it was blown.

As far as going with a Nissan part - they want $400 and they have to order it in. I'm not too concerned if the aftermarket part is a little noisier than the OEM - it was about 1/3 of the price.

Gemini67

Okay - I made a bad temporary connection - the new connection is solid and the fan works as connected according to Dennis' response, i.e. white with blue stripe is the power wire.

I went one further and broke apart the plastic housing around the motor so I could use the moulded plastic socket, then I tiewrapped the plug to the socket.

Thanks for the quick responses - much appreciated!!!

PJ

DennisMik

iTrader: (2)

The manual systems work like this. The auto climate systems use the "fan control amplifier" module and it is not a resistor. It is a transistor. Transistors will do one of two things - short or open up. If the fan control amplifier shorts, then the fan runs at full speed all the time, even when you press the OFF button. If the fan control amplifier opens up, then the fan never runs. There is no in between.

oldngivout

iTrader: (8)

http://www.courtesyparts.com/27070-m...3-p-47668.html

Hmm...

Gemini67

Two things... first, I'm in Canada, so it would have taken 3 or 4 days to get to me as there is no delivery on the weekends and overnighting it would just not happen - thanks NAFTA! Second, the motor was dead, dead, dead so I needed to replace it now - and NAPA had one so....

The $400 was a quote from a local Nissan dealer, little different from Courtesy, which would have been cheaper even with the USD/CAD exchange. I'm already aware of Courtesy and if it weren't such a situation, I would have ordered from them.

Gemini67

Hey Dennis,

Just to clarify - I have the Auto Climate Control - if the transistor fails I shouldn't get any fan at all? Or can the transistor fail one of the two ways you described (open or short)?

Weird thing, this morning on the way to dropping my wife off at the train, there was no fan. Then on the way back the fan suddenly came on, my replacement blower motor has been running fine since I did a proper connection, so I'm wondering if I have other problems too.

Thanks,

PJ

DennisMik

iTrader: (2)

if the fan control amplifier goes bad, it's bad. They don't become intermittent. I would guess that you have a connection problem. Since the new motor didn't have a connector, I would double check the way you connected it, especially if you didn't solder the connections. I am a firm believer in soldering. Twisting wires together is just creating a future problem.

It's also possible that the motor is "sticking". Got 2 things for you to try when the motor doesn't run again. First, wiggle the wires/connections. If the motor starts up, you have a connection problem. If wiggling doesn't help, then tap on the end of the motor with something, such as a screwdriver handle or small hammer. If tapping on the motor makes the motor spin, then you have a motor problem. If none of the above, then you will need to do voltage checking.

Gemini67

I appreciate the clarification - I was already thinking connection problem (arrgh!) I couldn't find my soldering iron, so I actually broke the old motor apart and used the connector by clipping the two wires that ran to the brushes. Then I twisted each wire separately, giving it a good dose of rubberized electrical tape, testing the connectivity BEFORE I taped them.

Maybe I cracked the connector, but I was pretty careful by nibbling away the plastic with a set of pliers.

What about the Power Assembly or Module (I think that's what it's called), it's located in the ducting underneath and is accessed by two screws and a wired assy - one wire looks like it runs to the blower motor.

Thanks.

DennisMik

iTrader: (2)

That power assembly you refer to is the fan control amplifier that I have been referring to. I don't think that it is your problem. And you are correct that one of the wires does to the blower motor. It is the blue/white stripe wire that applies ground to the motor.

Double check the splices you made, that has the highest likelyhood of being the culprit. Your worrying about having cracked the connector isn't worth the effort. The plastic connector is strictly to hold the electrical contacts in position/alignment so you can make all connections in one easy push. If the connector is cracked or broken, you just have to take a little more care when you plug the pieces together. The electrical connection is the metal pin in the connector. You get the metal pins in the other connector and life is good.

Gemini67

Wiggling the wires doesn't change anything - so I guess I'll treat it as a one-off for now and see how it goes over the winter.

Thanks again for your input Dennis!

Gemini67

Okay, this is driving me crazy!

Blower fan has been working fine (other than the one inop), until yesterday. Doing some shopping around the city, heater fan was working fine. After stopping at one store, no fan, wiggled the wires around - no change, so it I thought eff it, I'll look at it in when I get home.

Pulling out of the parking lot, I hit the power door lock switch and all of sudden the fan started. We were both surprised at that - saying that's weird! This morning, going to drop my wife off at the train station, no fan again. Then as I stopped the car, she hit the door lock switch on the passenger side and the fan started. WTF!?!

Do I have a possible bad ground - is the door lock switch tied into the blower circuit?

This is not good going into the winter.

Thanks,

PJ

DennisMik

iTrader: (2)

How do these wierd things happen?

There is no normal connection between the door locks and the blower motor. A bad ground is always a possibility and difficult to prove. The power to run the blower motor comes from 2 fuses under the hood by the battery that are labeled "Blower Mtr". The fuses feed the blower motor relay which then goes to one of the pins on the blower motor.

To make the blower motor run, the "A/C Auto Amplifier" (the a/c dash control panel) sends a signal to the "Fan Control Amplifier". This causes a variable level of ground to be applied to the other pin on the fan motor.

What you could try is when the fan doesn't run, hit the dash to the right of the glovebox. This would send vibrations to the blower motor relay, kind of the same as when the door locks operate. My thinking is that the relay is 'sticking'. This is a pure guess.

Gemini67

Thanks, I'll give that a try - next time the fan doesn't come on.

Is the blower motor relay a fairly easy part to replace?

DennisMik

iTrader: (2)

I have never seen the thing live and in person. According the the FSM, it is hidden in the section of the dash to the right of the glovebox, probably mounted on the sidewall of the car. I kinda think if you take the glovebox out, you will see it. Similiarly, I have never taken my glovebox out, either.

T_Behr904

Bumping this thread because I just experienced the same thing today. 2000 SE with auto climate control, and the fan quit working. Pressed the unlock switch when I pulled into my g/f's driveway earlier today and it immediately started working. Did it again not long ago and pressed the door lock switch and it immediately started working. Did you find the problem and what caused it? Figured I'd bump the thread and ask before starting a new thread on the situation.