jcunion413

Ok....

About a year ago, my blower motor stopped blowing completely out of the blue. Relays and fuses were fine so I grounded it and the motor spun up. So instead of looking at the root cause, I just ghetto rigged a relay into the circuit to complete the circuit when I turned on the Climate Control. Worked fine up until recently.

So I'm out today looking at the FSM and folowed all the preliminary and diagnostic precedures outlined in it and it told me to replace the Fan Amp Control. So here's the question...

Should the Auto amp be sending different volts to the Fan control amp. No matter what the setting the climate control is on (full blast or low) it sends ~9V. So should I go ahead and replace the Fan Control Amp or is there another test I can run?

If I'm not making sense I apologize. My brain hurts a little trying to figure this out on me own.

PS. I arrived at the voltage by grounding out the wire that runs from the back of the A/C Control Unit that runs to the fan amp control.

Any help is appreciated

mjmetcalf

I can't give you a definite answer, but judging by the fact it's called a Fan AMP Control (Amps are a measurement of current), and you say it's always about 9 volts, I would say it is probably controlling how much current is going to the motor rather than the voltage.

If your voltmeter does amps, try to hook it up to read the current. This is harder to do than checking voltage. You have to disconnect one of the wires to the fan, hook one of the meter leads to that wire then the other to where you disconnected it from. See what you get there for all the fan speeds.

Just an idea.

jcunion413

I'm probablly not being very clear. My head has been killing me all day lol

I don't think that it would be using any amperage because the blower motor isn't spinning. The way it works is it takes a signal from the Unit and sends X amount of voltage to the blower motor based on the signal it recieves. There are ~12 V coming from one side of the Blower Motor and slightly more coming from the side with the fan amp control. As far as the amount of amps being sent I haven't measured it yet but I would assume it was pretty close to nil.

So do I need to replace the Climate Control Unit or is there something I don't know about the Fan Amp Control?

Thanks

mjmetcalf

Let me make sure I got this right. You're measuring between ground and the two wires going to the fan. One is 12 volts (which I'm guessing is the ground side) and the other is more than that (the control side). I don't have my service manual with me now to check the schematic.

It sounds like there might be a broken connection between the ground side of the fan motor and ground. You said when you ran your own ground wire before it worked fine. There might be something wrong there.

Also, I used to have a GMC Jimmy that at one time, the fan blower acted up on. I fixed it by unplugging and plugging back in the connector. Dirty contacts. Maybe you got something like that too.

jcunion413

Yea I'm really confused on how it works but Yes, When both wires going to the motor are grounded they ready about the same voltage.

Now I'm pretty new to this consept of Voltage but this is my understanding on how it works. When I hook the ground side up to the fan amp control side and the Battery side up to where the flow of is coming from I get ~0Volts (more like .2) because electricity isn't being allowed to flow. The way the fan amp works (again to my understanding) it recieves a signal (x volts) and interprets and sends X volts to the blower motor. If it send 9 V to the motor, that means to motor is opperating on 3 volts. Basicaly when I grounded it, I closed the circuit and gave all 12 V coming from the battery a place to go.

Volts is a measure of how fast a current will flow but past that I don't know lol

ImmaSquashYou

iTrader: (7)

V=IR

You should get more voltage while its on full blast, and less voltage when its set lower. Measuring the voltage is good enough in this case. As the voltage goes up, the current goes up. As the voltage goes down, the current goes down. I'm not sure what it is doing now.

So, were u able to control the speed of the blower when you ghetto rigged the circuit? What is it doing now? Blowing at one speed or not at all. when you say you grounded the circuit, i'm assuming u grounded something in the relay?

jcunion413

When I rigged in the relay it would only turn at the higest speed (which was pretty damn high).

Yea I grounded it through the relay. Before then it wouldn't spin at all.

clive

Replace the blower motor, sounds like it is shot. If you still have probs it will be the climate control module.

mjmetcalf

I finally got a chance to look at my service manual. There are two wires to the motor, BRN/WHT and BLU/WHT. Brown is positive. Blue is negative. Brown is hot all the time. It looks like it comes in through Fuses 2 and 3. Blue goes to the Fan Control Amp. That has three wires, BLU/WHT from the motor, black to chasis ground, and BLU/YEL which looks like the control line. Measure the voltage on the B/Y wire. I would expect that to change as you adjust the fan speed. Higher speed is higher voltage.

It could be that you have two problems. Maybe the fan control amp and the blower blew out. If it was running off the rails for a year, maybe it just finally died.

good luck.

jcunion413

Thanks for the help guys!

The blower motor is still working fine, I used a jump wire to ground it out earlier today. As for the fan control amp, the B/Y wire that comes from the Climate control unit. Regardless of the setting it would always recieve ~9.6V from the Unit which leads me to believe that maybe the unit is bad.

Any other thoughts? Shoud I hit up the Junk yard and pull out a fan control amp before I abandon all hope?

jd885

What about the blower motor resistor... i have seen them go suddenly (and i know that when they go they usually only work on full blast) but sometimes they go and take all control away i would replace that first unless you already did considering they are only about $30.00

toyick

iTrader: (6)

mine did this same thing, i replaced the motor, took like 20 mins. and fixed the whole issue. i was able to get it to work either by hot wiring it, or hitting it with a hammer. plain and easy fix got a new one.and it worked fine!

mjmetcalf

Let me ask this. Do you have an automatic climate control or a manual control? I think automatic, at which point there aren't resistors. There's the fan control amp. In my service manual, there were separate schematics for the two and only the manual control schematic had the resistors.

jcunion413

It is the Automatic Climate Control.

I don't know why but I really hesitate to think that it's the blower motor. Notsaying it isn't but I'll probably hit up some of the local junk yards and see if they have any 4 gen maximas out there. At least that way I can rule it out.

mjmetcalf

Based on everything, my first guess would be the fan control amp. Second guess would be the head unit. The constant 9.6 on the control line is a little weird but maybe there is something internal in the amp that's making it do that.

jd885

damn i never new the automatic control didnt have a resistor.... guess i have never been fancy enouph for auto climate control lol

jcunion413

So I finally had enough. No junk yards had a maxima w/ climate control so I just rigged back in the relay.

Thank you everyone for you help. Take Care ^^

jcunion413

Right before I gave up, I shot my brother an email with the link to the FSM download. Just for general information, this is his take on it:

"Take a look at page HA-118. It describes how the auto amp works in conjunction with the fan control amp.



The 9.6 volts is a little high. But I’m not convinced that it is all that wrong. The Fan control amp is a switch that controls the current flow through the blower motor. This is solid state equipment. It is not as simple as V=IR in this case. Or at lest I don’t think it is. It basically pulses the current flow through the motor to control the speed. The input voltage from the auto amp signals the length of the pulses. It is an on/off function. You can’t trouble shoot it without an ocilliscope to know exactly what is going on. I’m still leaning heavily on the fan control amp. The auto amp would be my last choice. It would almost be worth the 100 bucks to let a tech at the Nissan place take a look at it and have him give you an opinion. You don’t have to let them fix it they can just troubleshoot it and give recommendations. I looked for a price on a fan control amp last night and didn’t come up with anything outside of going to a dealer."



If anyone else comes accross this problem in the future I hope that this helps.

valovich13

Is the Fan Control Amplifier located on/ right next to the blower motor housing? im having the same problem, my a/c works but i get no blow out of the vents... all fuses and relays are good... was looking for resistor but I have auto climate and did not find one... motor still works via a direct line check

pmohr

iTrader: (26)

Looking at your previous posts, you say you have an A33B? Why are you posting in this section (bringing up a 7 month old thread, much less)?


Or did you get a 4th gen?

Anyway, assuming you still have your '03...

Yes, it's next to the blower motor.

valovich13

I just searched blower motor for 03 maxima and this came up.... i didn't even look to see what year it was actually in... just figured since i put that in the search bar it would only show 03's