Howdy everybody,
Our '96 Infiniti J30's AC/ Heater blower motor crapped out. I've read through every associated post on NICO Club regarding my problem- possible Fan Control Amplifier; shot out brushes on the motor; etc.
Here's where I get lost. I tore into a '94 and a '99 J30 at a local wrecking yard today. Both heating/AC units were completely intact. I found absolutely nothing that even closely resembles the aluminum looking amplifier pictured in the post. What's up? Why would Nissan put this component on the Maxima and other models, yet skip it on the J30? Could it be hidden in a far away and out of sight place under the dash board? It makes no sense.
I removed a blower motor from a donor J30, just to be on the safe side. Man, what a pain that was. How in the world a person goes about changing the motor out on a J30 with out totally Brutus Beefcake'ing it, is beyond me.
I am open to all suggestions. Thanks a million, Amy

Welcome to the forums, badrock!

Nissan's engineers wanted this little puppy mounted next to the blower, so that the blower could force cool air across its heat sink. If they had mounted it somewhere else instead, it would have needed a much bigger heat sink, since it wouldn't have the fan to help cool it.

So, the best suggestion I got for ya is to hunt down a copy of the J30 factory service manual (or "FSM") - It should show the location of the Fan Control Amplifier on that model.

You can often find a copy of the FSM on a CD for just a few bucks on ebay, or you might even be able to find it online for free download.

Hi Skibane,
Two questions before I purchase the FSM:
1) Would extreme temperatures inside my parked j30 cause the heat sink to fry?
I cannibalized a blower motor and the housing from a 94 J30. On the outside of the housing, attached to motor's 2power leads is a blue plastic, square shaped electronic module of some sort.
2) Would Nissan install a plastic amplifier?

Check for the FSM on NicoClub.

Best to rehabilitate any used equipment to insure it will work on the long run.

Hey Skibane and everyone else on this incredibly helpful forum!

I have a 2002 Pathfinder LE which has been exhibiting symptoms of the dreaded Fan Control Amplifier issue for the past 2 weeks now. Upon turning on the ignition, the fan blows at full blast, regardless of whether the AC/heat is on or off. Additionally, the fan does not respond to fan speed adjustments -- it only blows full blast. It does, however, respond to changes in temperature and directionality (i.e. Feet, Head + Feet, Defrost, Defrost + Feet). Based on what I've read so far, these findings seem consistent with a blown FCA (as opposed to a blown fan motor). After removing the FCA, I saw that it contained the NEC K2500 MOSFET. Being pretty handy with a soldering iron, in addition to wanting to save precious $$$, I ordered the following parts from Digi-Key:

FDH5500_F085 N-Channel MOSFET: http://www.digikey.com/product-detail/e ... ND/2061557
Cantherm SDF DF141S Thermal Cutout: http://www.digikey.com/product-search/e ... DJ1+DF141S

I also ordered new air filters from http://www.courtesyparts.com to replace the disgustingly dirty old filters.

After soldering both components in place (and being careful to seat the MOSFET to the heat sink using Arctic Silver thermal compound), I eagerly re-installed the FCA in my Pathy. Unfortunately, upon turning the vehicle on, the fix failed to work. I am extremely puzzled...Based on this forum thread, it appears that I ordered the correct MOSFET. Did I order the wrong thermal cutout? Is something shorting that I'm not aware of (although my soldering looked very clean)?

Any thoughts would be greatly appreciated!

Best,
Erik

skulboep wrote:After soldering both components in place (and being careful to seat the MOSFET to the heat sink using Arctic Silver thermal compound), I eagerly re-installed the FCA in my Pathy. Unfortunately, upon turning the vehicle on, the fix failed to work. I am extremely puzzled...Based on this forum thread, it appears that I ordered the correct MOSFET. Did I order the wrong thermal cutout? Is something shorting that I'm not aware of (although my soldering looked very clean)?

When you say the fix "didn't work", I assume the fan is still running at full blast all the time.

Installing the wrong cutout wouldn't make the fan run all the time - It only prevents the fan from running if the cutout opens up - and it only opens up after being exposed to extremely high temperatures.

You might try unplugging the fan control amp from its connector, and using a DMM to measure the resistance between terminal "35" and terminal "G" on the fan control amp (i.e., the two terminals that go to thick wires when plugged into the mating wire harness connector).

If your replacement MOSFET is installed correctly, you should measure a pretty small resistance in one direction, and almost infinite resistance when you swap the probes on your DMM.

If you measure a small resistance in both directions, something's shorted internally.

Thanks for the help Skibane,

Yes, the fan is still running full blast (even when the AC/heat is turned off). I am, however, able to control directionality and temperature. I will remove the FCA and measure resistances with my DMM. If it turns out that everything measures out OK, where should I turn to next? The blower motor itself?

I'll keep everyone posted on how everything turns out and post some pics if I get a chance. I would be shocked if something indeed turned out to be wrong with the replacement MOSFET, as it's brand new...If this MOSFET does indeed turn out to be bad, is there another model I should try?

Thanks!

skulboep wrote:Thanks for the help Skibane,

Yes, the fan is still running full blast (even when the AC/heat is turned off). I am, however, able to control directionality and temperature. I will remove the FCA and measure resistances with my DMM. If it turns out that everything measures out OK, where should I turn to next? The blower motor itself?

I'll keep everyone posted on how everything turns out and post some pics if I get a chance. I would be shocked if something indeed turned out to be wrong with the replacement MOSFET, as it's brand new...If this MOSFET does indeed turn out to be bad, is there another model I should try?

Thanks!

Im about to try this on my 2002 pathfinder. Wondering how you made out???

Hey burgy240 email me i have a few questions about my fcar [email protected] and thanks

Since this board doesn't allow people to edit their old posts, here are the original images, re-hosted on a reliable, non-crappy, non-imageshack site:

Schematic for Y33 models:


Schematic for G50 models:


Removing the bottom screws under the glove compartment:


...and the top screws:


Location of the Fan Amp:


Fan Amp, after removal:


Where to unsolder, in order to remove the printed-circuit board:


Solder Wick - Very handy:


Using the Solder Wick to soak up hot solder:


Printed Circuit Board removed from Fan Amp housing:


Thermal Cutout removed from PC Board:


Replacement Thermal Cutout and Power MOSFET:


New Cutout and MOSFET installed:


Trim off the excess wire length on the Cutout, and you're done:

...and the re-hosted photos for the fan amplifier on Ted's Quest:

What this Fan Amp looks like:


With enclosure removed:


Top side of PC Board:


Original configuration, with 2 power MOSFETs (Q2 and Q3) installed:


Ted's modified configuration, with a third MOSFET (Q1) added:

[quote="Skibane"]

Hi Skibane, on your original post you had mentioned that you
had a few spare 2SD1297 Darlington transistors and thermal cutouts for the G50 version. If you still have them, may I buy them from you? I'm not electronics savvy, but I can follow your meticulous directions and solder-- if I had the parts, which I feel inept at attempting to buy, since most of the links no longer point to the original part, I'm sure I could fix my Fan Control Amplifier on my 2002 pathfinder. Thanks for your time and consideration.

Lemme check my stash.

BTW, welcome to the forums!

Thank you. This place is a wealth of information.

The Bad News: I'm out of the 2SD1297 darlington transistors used in the G50.

The Good News: I'm pretty sure I've located an acceptable substitute - for less than 3 bucks, in single-piece quantities.

It has a slightly different package than the original (the 3 pins are spaced slightly closer together) - But if you spread the pins, they should still fit in the pads on the fan amp circuit board.

I'm going to order 10 of 'em today from Mouser, along with:
- 10 thermal cutouts for the G50,
- 10 thermal cutouts for the Y33, and
- 10 of the FDH5500 replacement for the original 2SK2500 MOSFET transistors used in the Y33.

They should arrive within the next 48 hours.

If anyone wants to buy one or two transistors and cutouts for either the Y33 or G50, I'll gladly sell 'em to you at my cost. No large quantity purchases, please!

Hi Skibane,
I'm glad to see you are still contributing to this thread. I own a 2001 Pathfinder LE with 147,000 miles on it and it does not have a Navigation System. Instead it has the Automatic AC Control panel that provides 4 blower speeds. I have read Skulboep's post who owns a 2002 Pathfinder. Rather than buy the same parts he purchased to fix his Fan Control Amplfier which ended up not working, I would appreciate it tremendously if you can post what is the correct MOSFET and Thermal Cutout I need to buy for my 2001 Pathfinder. Also for my 2001 Pathfinder does the Y33 schematic apply or does the G50 schematic apply?

As for the AC problem I'm currently experiencing I can describe it this way. My air blower does not spin after I press the Power On button on the AC Control Panel and it lights up. Therefore, I removed the glove box and discovered that if I tap my Fan Control Amp unit with my socket wrench the air blower starts spinning. However, tapping on the Fan Control Amplifier with my socket wrench does not always result in kick starting the air blower fan. This is like the third time my Fan Control Amplifier has failed on me. I'm tired of buying this part from the Nissan Parts department only to have it fail shortly after the Nissan 1 year warranty expires. I hope by fixing it myself I will have better luck with this thing not failing so soon again.

Any help you can provide that will lead me to buying the correct parts will be greatly appreciated. Thanks in advance.

binar01011 wrote:As for the AC problem I'm currently experiencing I can describe it this way. My air blower does not spin after I press the Power On button on the AC Control Panel and it lights up. Therefore, I removed the glove box and discovered that if I tap my Fan Control Amp unit with my socket wrench the air blower starts spinning. However, tapping on the Fan Control Amplifier with my socket wrench does not always result in kick starting the air blower fan.

From your description, it kind of sounds like your blower motor is on its way out.

Typically, when it's going bad, you can "jump start" it by whacking on the outside of the motor - But I wouldn't be surprised if whacking on other stuff located in the same area could also cause it to start.

Skibane,
Thanks for your post. I will be visiting several car recycler yards to see if I can find a good secondhand air blower. But to further my Pathfinder 2001 LE AC education can you please let me know the following:

Which of the two applies to a 2001 Pathfinder LE, a Y33? or a G50?

Also can you please post your opinion on what you believe is the best MOSFET and Thermal Cutout substitute for a 2001 Pathfinder LE?

I will be very grateful if you can address these two questions. THanks.

binar01011 wrote:Skibane,
Which of the two applies to a 2001 Pathfinder LE, a Y33? or a G50?

Nissan's 2001 Pathfinder factory service manual shows a MOSFET transistor (highlighted in green) being used for the Fan Amplifier, instead of a bipolar Darlington transistor:



The Y33 also uses a MOSFET, instead of the bipolar Darlington used in the G50 (which kind of makes sense, since your Pathfinder and the Y33 were produced in roughly the same model years).

So, the FDH5500 MOSFET transistor and 145 degree thermal cutout used in the Y33 are what I'd try.

If you'd like, I can sell you one of each, at the same price I bought them from Mouser - I'm not making any money on this.

Skinbane,
Thank you very much for your excellent post. That is tremendous help. I will be sending you a message regarding your parts.

Hi Skibane. Thanks for the great info on fixing the always high speed blower running issue. My 2002 Pathfinder LE has had this problem twice; first at 184,000km and now again at 254,000km. The dealer wants $240 CDN for a replacement module. My module shows a Source to Drain short circuit.
Do you still have any MOSFETs for sale as I would like to repair my modules? Not sure if we can do private messages, but if so I will send my address and you can let me know how to pay for the part. Cheers

Rotoroff wrote:My 2002 Pathfinder LE has had this problem twice; first at 184,000km and now again at 254,000km.

Typically, a bad blower motor contributes to the controller's early demise.

If you haven't done it already, please consider replacing the motor.

Do you still have any MOSFETs for sale as I would like to repair my modules?

Yep!

Hi Skibane. Looks like you have a fix to a problem I have. My 2002 Pathfinder LE fan is always on high at any temp and whether or not it's on. May I also purchase a MOSFET and cutout from you? I'm not entirely clear yet of all the parts I need. I joined a few minutes after reading your initial post and I can't figure out how to send you a private image. Please contact me if you have more. Thank you!

Hi gang! New member here and I want to really thank you guys for this thread, and more importantly, for keeping it alive and updated for 7 years!! Truly a Legacy thread...

Skibane, big thanks to you, especially!

I just bought a 2000 QX4 for a very low price with the explicit understanding that I would have to put some money and work into it to bring it up to a reliable daily driver. I realize its 16 years old, so it won't ever be perfect, but even carfax said it was a recommended buy at that price! The HVAC isn't a "do or die driving" problem, but, it seems like one I might be able to do on my own. My first few searches lead me to this forum and thread, and I think my problem fits into this mold:

Everything HVAC _looks_ like its working (lights, door noises, speed adjustment, temp adjustment, etc), but I never get any actual air. The only time I _do_ get air is on the highest fan setting while traveling at higher speeds and I've read that the air coming in isn't actually fan/blower related, its just from having the vent doors wide open. There is no intermittent "on sometimes, off more often" ... "comes on if i hit things" ... no "stuck on high at all times." None of that. Just no air.

I looked at the fuses and one of the Blower fuses was blown (J/B, #1, I got all excited, but sadly, that wasn't the primary cause) and the second Blower fuse was a 20A, instead of the 15A it should be. I pulled out the 20A and put in the right one, but, again, no such luck. I'm hoping the 20A didn't eff things up beyond repair, as I've been reading the Infiniti factory service manual, and they say never to use a fuse with a higher rating.

At any rate, seeing as I'm very budget-minded, I figured I'd jump into the fix detailed here, but I want to make sure I'm doing everything in the correct order. I checked the driver-side fuses, replaced 1 blown/"open" 15A fuse in the fuse box J/B, position 1, and replaced an in-place 20A fuse with the correct 15A in J/B position 2. I ran through the self-diagnostic for the HVAC, with mode 2 always coming back "25" (even in direct sun). I've read that sometimes the blower fan can be jammed up with dust and other nastiness, but mine was totally clean. I spun the blower fan by hand a few times and it spins around with ease. I took a look at the fan control amp to see if there were any obvious signs of it being broken, but I couldn't tell, so I put everything back in with the hopes that just a little re-wiggling doing the trick, but no such luck.

(A couple other things are problematic, but I think because of their own, separate issues. I'm mentioning them only because they are in the general vicinity of the HVAC: Along with the HVAC never blowing air, the Radio illumination goes on and off intermittently. Everything audio works well enough-- it doesn't fade out occasionally and the radio/audio always works, whether the radio lights are on or off. Also, the AIR BAG light on my main dash constantly blinks. Could be any number of things, but I mention it because of possible HVAC interaction. Maybe its blinking because someone previously tried to fix the blower and somehow screwed it up?)

Have I missed anything? I've haven't spent much time with a digital multimeter, tho I do own one. I'm a relatively quick learner, so I figured I'd start off with a quick youtube lesson on how to use my DMM before delving too deep into the project. I've also read that replacing the blower motor and fan control amp at the same time is recommended. Should I just bite the bullet and spend the, what $400?, to buy both parts and self-install, and hope it doesn't burn out again too quickly?

Anyway, sorry for this monster wall of text, but I figured I'd be as thorough as possible. Thanks again for all your help and effort, Skibane and crew!

Infiniti4Me, you might try removing the fan control amplifier, temporarily soldering a wire across terminals "35" and "G" on it, and then reinstalling it.

By soldering the wire, you're providing an alternate path for blower current. If the blower now runs, you know that either something inside the fan control amp isn't working (i.e., blown MOSFET transistor), or the control amp isn't getting a control signal from your AC Auto Amp.

If the blower still doesn't run, you know that either the blower motor itself is bad, or it isn't getting battery power (fuse blown or bad connection).

I certainly wouldn't spend $400 on parts until I knew for sure what was causing the problem. Your fix might turn out to be something as cheap as soldering in a new MOSFET.

I still have some of the FDH5500 MOSFETs (for the Y33-style fan amplifier) and 2STW100 Bipolar Power Transistors (for the G50-style fan amplifier), as well as the thermal cutouts. As always, I'm selling them for the same price I paid for them. Shoot me a PM if you'd like to order something.

Skibane, thanks for the reply! The Dashboard says I'm still too new of a member to do any messaging.

I'll give the temp soldering a try and get back to you, but, yes, I am interested in buying the replacement parts from you, if I need them.

Thanks again for the help. I'll get back to you in the next day or so.

Hi, Skibane,

Well, I didn't want to hound you with stupid questions, but looked and looked and decided to err on the side of safety and caution. I can't figure out what you mean when you say "temporarily soldering a wire across terminals "35" and "G"." I see the labels "35" and "G" on the diagrams (the two "bottom" prongs), so do you mean I should solder a wire from prong to prong?



So, solder wire where the red squiggle is in my image?

https://goo.gl/photos/n3feKZWoqeduW8ZR8


Thanks again!

Yep!

In fact, they're close enough together, you probably wouldn't even need to use a wire. A solder blob is probably all you'd need.

After you're done, heat both pins with your soldering iron, and immediately rap the Fan Amp on something hard to dislodge the molten solder.

Well, poop! I tried connecting "35" and "G," as suggested, and no-go... no change: controls work, everything seems to be okay, just no air. Self-diagnostic comes back okay. So, I guess its back to testing harnesses and whatnot? -- Tho, I did get a brand new, shiny, on-sale, $10 DMM to use this time! I re-tested the various terminals on the FCA, and most every combo was either just 1 (which is infinite, right? which indicates "open" or bad, right?) or returned a very low read-out for about 1-2 seconds, then went back to 1.

How do I supply power directly to the blower motor to see if it spins at all?

thanks again!

The Good News: Your fan amp isn't the cause of your problem - And probably won't require any repairs.

At this point, I'd probably just remove the blower and temporarily connect it directly to your battery - just to see if it spins.

I'm betting that it's dead - In which case you would have needed to remove it to install a new one anyway.

It's been a while since I replaced mine, but I don't remember it as being a very difficult job.