How to fix your Fan Control Amplifier (updated)

Post by **Infiniti4Me** » Fri Feb 19, 2016 9:32 pm

Quick update: I took out the blower and tested it off the car's battery, directly, and it spun just fine. I got all frustrated and decided to give up, so I put it all back together. The next day, as if nothing had ever been wrong, the blower came on and now works just fine! Heat, A/C, fan, everything! So, a wire or harness or connection must have just been loose or something. I'm keeping my fingers crossed, but I bet I'll be back here again soon! lol

Thanks again!

Post by **Skibane** » Fri Feb 19, 2016 10:37 pm

When a blower is on its deathbed, it may still work part of the time.

Often, just whacking on the motor housing will get it running again for a while.

So, I wouldn't completely rule out your blower as being the cause of your problems just yet.

Dlo024 · Post by **Dlo024** » Tue Aug 09, 2016 5:37 am

Hey Skibane thank you for helping us with all your amazing contributions ! I have a problem with my 03 M45 (y34) with 80k : for the last 2 months sometime when I start the car the ac will go on full blast and the nav/climate display will turn on but nothing will show ...also the climate/nav/radio buttons wont work. When go over a big bump i will start or stop working again and after a hot sunny day (when the cabin is hot) it will start working again.

My question is : do you think the problem is related to the fan control amp and if so does the Y33 and Y34 have the same schematic?

Thank you

Post by **Q451990** » Tue Aug 09, 2016 7:49 am

With the the control buttons not working, I don't think the fan control amp is your issue.

Post by **Skibane** » Tue Aug 09, 2016 11:31 am

Yep - The fan amp only controls the fan - It has absolutely nothing to do with the nav or radio buttons.

Since your unit goes all wonky when you hit a bump, it sounds like you have a loose connector - or maybe a screw that connects a wire harness to chassis ground needs to be re-tightened.

If any wiring was unplugged or disconnected from a ground point during a radio install or other repair, that's a good place to check first.

Dlo024 · Post by **Dlo024** » Tue Aug 09, 2016 8:01 pm

Thank you guys for the quick response

Post by **24SevnLibrarian** » Sun Oct 02, 2016 8:48 pm

Thank you all for sharing your knowledge and experience. This has by far been the most helpful source of information on what may be preventing my 2006 Pathfinder's air from coming on sometimes until I hit the dash in the right place (or enough times, whichever it may be). Once the air comes on, I can change the strength, but even on max, I know it's not blowing as strong as it should. When I hit a bump in the road, it occasionally blows out harder, but never with the strength it should have. I have taken out my blower motor to try to look at the brushes, but for the life of me, I cannot figure out if and what I am supposed to take apart to see inside the blower motor. Maybe I'm confused and it's not supposed to come apart. I would love some advice. This is a new experience for me, but I want to learn how it works and fix it myself if possible. Thanks so much!

Post by **Skibane** » Sun Oct 02, 2016 11:48 pm

Welcome, 24SL!

The fan motor really isn't designed to be a "serviceable item" - It's pretty much a throwaway part.

The original Nissan part is kind of pricey, but there are also plenty of aftermarket versions that won't break the bank - For example, here's a link to Rock Auto's inventory for the 2006 Pathfinder.

Post by **24SevnLibrarian** » Tue Oct 04, 2016 10:03 pm

Before I buy a new blower motor, is it the most likely part responsible for the:
AC occasionally not coming on until I hit the dash right over the left corner of the glove box,
Max AC blowing more weakly than vented air,
Max AC air strength much less than it was in the past?

The air is cold, just weak. At the highest setting on recirculated air, it feels more like a middle setting. In the winter, the air takes much longer to get warm than it used to. Obviously, I've been putting off taking care of this, mainly because I don't have the resources to pay someone to "fix" the wrong parts. After paying to have the transmission rebuilt due to the Nissan coolant issue and replacing 2 catalytic converters and one ignition coil, I'm tapped out but in too deep to give up. :-)

Post by **Skibane** » Thu Oct 06, 2016 12:37 am

24SevnLibrarian wrote:Before I buy a new blower motor, is it the most likely part responsible for the:
AC occasionally not coming on until I hit the dash right over the left corner of the glove box

Yes, if you mean that the blower occasionally doesn't come on until you hit the dash in the proper spot. That's a classic symptom of a blower motor on its deathbed.

Max AC blowing more weakly than vented air

Yes, particularly when you're driving real fast.

Max AC air strength much less than it was in the past?

Yes.

Post by **24SevnLibrarian** » Fri Oct 07, 2016 8:32 pm

Thanks so much! I'll let you know if it worked once I get the motor.

Post by **24SevnLibrarian** » Wed Oct 12, 2016 4:50 pm

I think my car knew something was up, because I haven't had to hit the dash for the past week to get the AC to blow. Course the temps have been much cooler. Got the blower motor this afternoon, put it in, and the air seems stronger. I'm going to forego the sunshades tomorrow and see how it feels when the car interior is much warmer. The only thing I noticed (besides how dirty the old motor was compared to the bright white new one) was that I could actually hear the fan turning. I don't know how to describe it, maybe like the difference between an old ceiling fan that works fine but isn't as quiet as the newer ones? But hey, it works, so I'm okay with that! Thanks, again, for all the help!

Wildride70 · Post by **Wildride70** » Sat Dec 10, 2016 12:06 pm

I'm new so excuse me,but why can't I access the images in the original post?
ie:schematics,photos etc. I click and nothing happens...

Post by **Skibane** » Sat Dec 10, 2016 11:17 pm

Wildride70 wrote:I'm new so excuse me,but why can't I access the images in the original post?
ie:schematics,photos etc. I click and nothing happens...

The original photo links have expired.

However, the photos are re-posted (with good links) on Page 5 of this thread.

Wildride70 · Post by **Wildride70** » Sun Dec 11, 2016 7:54 am

Thankyou Skibane,I appreciate your help!

Post by **my12by60** » Mon Jul 20, 2020 11:32 am

I just used this write-up to diagnose and remove/replace my fan control amp. Thanks to skibane for putting this together, as it continues to add value for Q owners.

My son primarily uses our Q now. He reported "AC is dead". I went to check and quickly figured out that the compressor and clutch sounded fine under hood, but we had no air blowing at any speed. My first thought was fan motor. Then I did a search and found this thread, which suggested that the amp is a more common failure part. Since my soldering skills are remedial at best, I instead just bought a replacement part on Amazon for $18. The swap out was easy with the pictures provided and we now have the fan motor working again at all speeds.

I realize that the fan motor may be on its way out and that may have fried the amp. So I am keeping my fingers crossed that the fan motor is still good and won't fry the replacement amp. Finding a replacement fan motor is not cheap right now. The only thing I could find online was at partsgeek.com for $282.

Post by **3Q Jay** » Mon Jul 20, 2020 1:00 pm

good to hear!
I had no idea that there were aftermarket control amps available. There were slight differences between the amps used in the G50 and the FGY33, so I'm not certain that the aftermarket part is suitable for both platforms.
Regardless, I would not worry about your blower motor. yes, it could fail, but anecdotally I replaced the amp on one of my G50s 10 years ago, and left the blower and everything is still working properly today.

Post by **my12by60** » Mon Jul 20, 2020 3:17 pm

Yes, the aftermarket amp was available on Amazon, even with next day delivery. And I had a choice of about 5 of 6 other options, but I wanted the next day delivery. After all, it is July in Phoenix and my son was not loving life with no AC.

Post by **3Q Jay** » Mon Jul 20, 2020 5:27 pm

I've been to Phoenix in July..... The OAT gauge on the G50 read 118F in the afternoon driving the stretch b/n Casa Grande and Tucson. I had the A/C set to 81, and the air coming out of the vents was at 39F just to keep up. I had stepped out for a quick visit with Joe at IoS, when it was only reading 115F....my lungs felt like they were on fire, just walking from the car to inside the showroom.

Post by **Skibane** » Mon Jul 20, 2020 6:19 pm

Once again, since this board doesn't allow people to edit their old posts - and I can't guarantee how long the images on Page 5 will continue to be hosted - here are the original images, re-hosted from another web source:

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:

[/quote]

Post by **Skibane** » Mon Jul 20, 2020 6:21 pm

...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:

Post by **Q451990** » Tue Jul 21, 2020 8:35 am

Thank you!

Post by **attofarad** » Thu Dec 31, 2020 2:33 pm

Just a note regarding the FDH5500 replacement: the dimensions are different from the original FET, in that the plastic extends further past the hole (away from the pins). This causes the clip that holds the thermal cutout not to sit quite right. I used my Dremel tool to grind off the edge of the plastic just a bit, until the clip sits correctly when the holes are alighed, and the thermal cutout is held securely against the heat sink.

My original lasted 15 years. A replacement ($$ dealer part $$, I had to have it quick) lasted just under 4 years. I hope my repaired part (replaced power FET) lasts longer.

Here's a link the the "permanent" article, which doesn't have the disappearing pictures problem: https://www.nicoclub.com/archives/fix-t ... issan.html

Post by **VStar650CL** » Thu Dec 31, 2020 2:49 pm

The FDH5500 is a great part, a big improvement over the original NEC chip. However, if you keep popping amplifiers or they don't last as long as they should, there's a good chance your blower motor has a hidden issue. See this post:

Blower Basics

Post by **BCC93QT** » Thu Dec 31, 2020 9:58 pm

1990... my blower motor screeches slightly when cold.... annoying but goes away when cabin warms up. Also... anyone ever see this before?

Bad quality as my camera lense is cracked and I was driving red lines

Post by **VStar650CL** » Thu Dec 31, 2020 11:19 pm

Dunno about the pics, but a startup screech is usually a bad tail bushing. The pressure from the brush springs will tend to center it as it spins for a bit. Probably harmless until it eventually seizes, but then it'll take out the amp when it dies. On most of them you can pop the tail cover and lube it up, that will usually kill the noise for awhile.

Post by **Q451990** » Mon Jan 04, 2021 4:29 pm

Is it the red lines you're asking about on the screen?

Post by **BCC93QT** » Mon Jan 04, 2021 4:48 pm

Yes I see the red lines from time to time. Months apart. not really a big deal but just wondering if it's common or if people have seen it before

How to fix your Fan Control Amplifier (updated)

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