Awesome post Solara! You just took all the guess work out of this DIY fix.

The filters I got didn't come with stickers or a new clip. Maybe that's why the numbers were different? You're right, it's best to call to speak with a live person to ensure you get the right parts.

Happy motoring!

Andrew

PivoArch wrote:Ok, The instructions that come with those filters say to cut the black box that would contain the filters in order to replace the ones that are in there. (Is that common?) When I cut open the box there were no filters in it, so I was just curious if I am in the right place or am I completely off base trying to replace the in-cabin filters?

The Pathy does not come standard with cabin filters. If you want to install them, then yes, you do have to cut/remove the plastic knockouts where the filters go. I had to do that on my 02 Pathfinder. The knockouts are there to prevent air leaks when there are no filters installed. The filters I bought by the way, came with clips.

Andrew224 wrote:You are looking in the wrong place. I have no idea what you just cut. You should not have to cut anything! Like the engine air filter, these filters were designed to be replaced fairly often. You should only have to pop one small clip off to get them out and replace them.

There should be nothing that needs to be cut. The filters are just to the left of that amp. you replaced. There is a small metal clip that needs to be popped off with a common screwdriver and the filters will slide out one at a time. They are stacked on top of each other. You can see the grey plastic edge of the filter next to the area where you were just looking. The filters may even have a part number printed along the edge. The filters fit in so that the air passes through them left to right and you will be looking at the skinny, hard plastic edge.

See my post above. Not all vehicles come standard equipped with cabin air filters. The 02 Pathfinder being one of them. It does need to have the slot cut out. Hope this helps, and that it's not too late for my input. I ordered my filter kit from Courtesyparts.com by the way. Quick delivery and much cheaper than my local dealer.

Buzzman wrote:Not all vehicles come standard equipped with cabin air filters. The 02 Pathfinder being one of them. It does need to have the slot cut out. Hope this helps, and that it's not too late for my input.

Thanks for confirming that for me I was begining to think that I had cut something I wasn't supposed to.

Thank you all for this post!!!!

I think I have the same problem with the Fan Amp. I have taken everything apart. I get voltage at the fan amp, not at the fan motor. I've checked the fuse and the relay, they are fine. Looks like I'll but the replacement fan amp tomorrow.

thanks,Brian

I picked up a set of filters for a 1998 pathy, removed the glovebox and then couldnt find the filters. I put it all back together and figures id tackle it another day. I searched the net and found this thread. wow what a relif. - nico rocks

Anyhow the filters i picked up are not OEM so i dont have the "cut the box" instructions. can you post up that part of the instructions??- this isnt some thing i want to mess up on.

thanks!
Modified by GTIRNN14 at 9:25 AM 6/6/2008

Instructions can be found heRE:

http://www.courtesyparts.com/i....html

thank you very much!!

I have a 97 QX4. I replaced the blower motor in October of 07 and now it's doing the same thing. Sometimes it wont blow at all and other times it blows real hard. When it wont blow at all, usually if I give it a good tap under the passenger side dash the blower will kick on and blow great untill I turn my car off. When I start it back up sometimes it comes on full blast other times nothing untill I give it a wack! Do you think it could be the amp thing you guys are talking about? Please help I get very grouchy when I am hot! In fact I am sure people who commit road rage have no ac! Thanks for any help at all!

What if I have power to both the fan amp and the blower motor? Do you sitll think it would be the fan amp? As of right now I have no fan at all but the digital controls in the dash still work.

thanks

I would say yes for the last two questions posted. But again, I'm not an expert by any means.

Andrew

Thanks for the great information. The dealer here on St. Croix wanted to replace the entire contral assembly for $1000. I ordered the AMP and filters on the Courtesy Parts website for $110.00 and had the problem fixed in ten minutes. If you ever get to St. Croix I'll buy you lunch and dinner!!

I am new to this!I have a 98 Pathfinder and recently the blower motor will just shut off. The next time I get in it the fan does not always come back on. I changed the fan control knob and that did not do the trick. I put a meter on the wires at the fan and when the fan is working my voltage is good, and when the fan is not working the voltage is not there (so I assume the fan is still good?).Any Ideas?

Since I couldn't find a replacement for the original MOSFET, I looked for a replacement. I got a package of ten IRFZ44V via E-Bay (from Hong Kong!) for under $10 including shipping. I replaced the Mosfet in the Fan Amp and nothing happened.

But then, I traced the circuit and found the control signal passed through a small component also mounted to the heat sink, which I couldn't identify. So on a whim, I shorted across this component... and my fan started running!

My best guess is that this component is a thermal cut off switch. Built to burn out if the heat sink gets too hot. (Now, they could have put in something with a reset button, but then they couldn't sell an expensive replacement part.)

I decided to replace the unknown part with a 10 K ohm resistor. It works with the new Mosfet just like new. I don't know if the original Mosfet was even bad... probably just the 'strange' part burned out. But since it is working, I didn't bother swapping back the old part to test it.

I'm going to look to see if I can find a replacement thermal cut-off component, but until then... it works!

Here are the steps:1. Follow the excellent pictures from Solara's post to remove the fan amp.2. Remove the white plastic cover from the fan amp.3. Unsolder the 3 connections on one end of the circuit board and the two connections on the other end. (Melt the solder while gently lifting the circuit board and work your way around making a millimeter progress or so at each connection until all are free.)4. Remove the screw holding down both components to the heat sink.5. Remove the 'strange' component (the one with two leads).6. If needed, replace the Mosfet... you may not need to. If you do replace it, use thermal grease. The whole heat sink gets REALLY hot... you want good conductivity. You can probably get thermal grease from Radio Shack.7. Tighten the screw back down. If you replaced the Mosfet, you may need to add a washer, as the replacement part is physically smaller than the original.8. Solder a wire or a resistor (0 - 10K ohm) onto the circuit board at the two-connector end (where the 'strange' component was removed). The resistor need not be physically mounted to the heat sink as was the 'strange' part.9. (Optional) solder short insulated jumper wires to each lead of the Mosfet, so if you need to disassemble this part again you won't have to repeat the pain of going through step 3.10. Solder the 3 Mosfet leads (or the jumper wires) back onto the circuit board.11. Reassemble and mount back in car.12. Better change out the filter (again, see the pictures above), since the clogged filter probably caused too little air flow, which caused the fan amp to overheat, causing the thermal fuse to blow in the first place. (I think I'll try using some material from a home furnace filter, under $2, stuffed into the original plastic frame rather than pay $20+ for the replacement part.)13. Test it out... hope it works for you!14. Legal disclaimer... how stupid that lawyers have forced us into this... the 'strange' part may be crucial to the safe operation of this system. By removing it, you may be placing property and perhaps lives at stake. I do not know the original purpose of this part. Its removal may burn out the whole electronics section of your car. It may allow the fan amp part to overheat and melt the surrounding parts or even start a fire. It may void your vehicle's warranty. (If you believe in chaos theory, it may cause world war 3.) Concern over these effects could raise your blood pressure and perhaps cause a heart attack and possible death. On the other hand, it may just work.

I just recently started experiencing one of the issues mentioned in this thread on my '02 Pathfinder: climate control fan runs on high and will not shut off. The tech at my dealer today said I needed a "blower motor kit" and the cost was an ugly $415. This on top of the $85 I paid for the diagnostic and I'm not certain that $415 includes labor. They ordered the "kit" but I have not committed. Does this sound legit?

have them give you a breakdown of whats in the kit, if they wont tell you what parts they are trying to pass off as a "kit", then they arent worth dealing with. most likely all you need is the fan amp which isnt $400.
Modified by timmack at 6:36 AM 12/19/2008

Okay, I just spoke to my dealer further about this issue. They claim only replacing the amp is a Band-Aid and that the problem will recur as there is an issue with the blower or blower/amp combo, thus the need to replace the whole thing. Any thoughts on this? Has anyone who has only replaced the amp had the problem happen again?

I replaced my amp back in March and have had no problems with it since.

I replaced the fan amp. in my friend's truck about a year and a half ago (where this post originated). He never had an issue again.

I've never heard what you've been told. In fact, when mine went out in my truck (an '01 QX4) about 3 months ago, I took it to the dealer (it's under an Infiniti extended warranty) and they just replaced the fan amp.

My opinion is that unless your truck is under warranty, which it doesn't sound like it is or you wouldn't be here, you should just replace the fan control amp. yourself and save a few crisp hundred dollar bills.

Andrew

Thanks to everyone for all of this amazing info! I'm not having any blower amp issues but I did remove my in cabin filters a few minutes ago which have over 180,000 miles on them and wow, those things are nasty! I had no idea they were even there so they never got replaced.

Thanks again!!!

Billy

According to the TSB, linked below, both the blower fan and amp need to be replaced.

http://www.nissanhelp.com/Owne...7.htm

-or-

http://x.nissanhelp.com/forums...age=4

2000 QX4 with the same symptoms as the initial poster. All fuses look OK. I have replaced the blower fan and the amp and I still have the same problem. I have gone through the diags found in the service manual and can't get beyond #4 as I have nothing coming out from any of the air vents. I put my hand on the new blower motor and it feels as if it is moving however there is no air coming from the vents....Any suggestions?

I had the dead fan problem with my wife's 1999 QX4 about a year ago. After using this site to track the problem down to the Fan Control AMP module, I disassembled the AMP module and tracked the problem down to the failed component within that package. The component that fails within this module has a custom part number that will not cross reference to a standard replacement component (I think an NEC number on mine if I remember correctly). However, after a little more research, I decided to take an educated guess at what the component was and went with an N-Channel MOSFET.

I replaced the failed component within the metal case (making sure to properly re-heat sink the replacement component since all fan motor current is driven through this small part). You will have to solder the part into place, but there are only three pins on the part, so it's a fairly easy repair. The repaired amp module has worked perfectly fine. We haven't had a problem in over a year now. The replacement component costs about $3.

That takes the repair of this problem from a $700 dealer repair, all the way down to a $3 component replacement if you are willing to get out your soldering iron. Use the directions from another author in this thread to remove the AMP module metal can (The pictorial instructions provided in this thread are excellent). Then open the can and find the only part that looks like the one pictured in the link below.

A link to the replacement part follows:http://parts.digikey.com/1/par....html

This fix took the $700 dealer repair beyond the savings of going with the $120 module replacement - all the way down to a $3 component replacement.

By the way, there is also a thermal fuse in the module. Mine checked out ok with the ohm meter, but I replaced it also anyways since I had the module opened to replace the MOSFET. The part number I used for that component follows:http://parts.digikey.com/1/par....html

I hope others can have the same success in savings I had with this repair.

This worked for me.....AWESOME.....replaced the part...I'm back in BUSINESS!!! Thanks for the detailed instructions!

WOW! I'm sooo happy! I love you guys! I replaced the mosfet for giggles and then the resistor with parts that cost 3.50 from http://www.digikey.com/ and my ac works like brand new now! I'm amazed, this was gonna cost me close to $1k at the infiniti dealership! I owe u guys a beer (quite a few) if you're ever in Fresno!

that is very odd because i have an 02 and i didnt have to cut anything!

OK, so I read through all these posts and have what i think is a similar problem. However, my fan still works on all speeds, but makes a horrible screeching/clicking noise under the glove box. I have to turn the AC off then back on several times in order to make it stop (which doesn't always work). Do I have a blower motor going out or the amp problem?

That sounds like the blower motor is going. The amp going most likely would not have any noises associated with it.

Andrew

How much are those and is it just as easy as changing the amp? Is it located in the same general area and should I change the filter at the same time? I appreciate any help.

It's a little more in depth than the amp. but in the same general area. Use the instructions from page 1 of this post to get to it. Take the glovebox and panel behind it down and then turn the a/c on. You'll get a better idea of what's causing the noise. If your filter hasn't been changed in the past year or two, I would change it. I have no idea what a blower motor costs.

Good luck,

Andrew