How to fix your Fan Control Amplifier (updated)

A Q45 forum / Cima forum for the President of Infiniti's lineup. Brought to you by Infiniti Parts USA, your OEM source for Q45 parts!
User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

ted emailed me some photos of the Fan Control Amp in his '02 Quest.

Image
Bottom side of the Fan Amp.

Image
Top side, with enclosure removed.

This is a much more modern design than on the Q45's - It uses pulse-width modulation to adjust the fan speed by rapidly switching a pair of MOSFET transistors (Q2 and Q3) on and off. Longer pulse on-time = faster fan speed. Shorter pulse on-time = slower fan speed.

Image
The heat sink is attached to the transistors with a metal spring clip. Popping off the clip allows the heat sink to be removed.

The fact that Ted's fan runs at full speed all the time is a clue that Q2 or Q3 might have an internal short between their Drain and Source terminals. Since they're both connected in parallel, a short in either one would effectively prevent the other one from working normally.

On a hunch, I suggested that Ted replace both transistors. They're available at Mouser Electronics for around 2 bucks apiece (link here.)

Interestingly, the PC board has provisions for connecting a third MOSFET (Q1) in parallel with the other two. Apparently, some engineer decided later that having just two MOSFETs would suffice (which in hindsight might have been the wrong decision!).

Image

Along with replacing Q2 and Q3, Ted decided to also install a third transistor in the unused position where Q1 is on the PC board, on the assumption that spreading the fan motor current among 3 transistors would reduce the chances for another transistor failure.

Image
(shown with Q1 Photoshopped into image)

Ted reports that the Fan Amp now works normally - so the repair worked.


maxnix
Posts: 22628
Joined: Mon Jul 22, 2002 8:11 pm
Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45

Post

Nice follow up! And well photographed pictures, Ted.

Neilg71
Posts: 1
Joined: Fri Jan 13, 2012 8:38 pm

Post

Your control amp circuit board looks identical to that on my 2003 X-Trail. It looks like a bit of a weak spot on the Nissan, but your diagrams and instructions are worthy of any Haynes manual! Many thanks

User avatar
Q451990
Moderator
Posts: 11473
Joined: Tue Jul 23, 2002 8:21 am
Car: 1990 Q45 - 118K, 2022 Toyota 4 Runner, 2004 Frontier M/T - 108K, 2012 Xterra (Mom's), 2023 Rogue (Inlaws)
Location: Columbia, SC
Contact:

Post

:welcome: to NICO Neilg71!

Heath

paulbrev
Posts: 1
Joined: Mon Apr 23, 2012 8:18 am
Car: 2003 pathfinder

Post

Hi ,
I just came across your post.
I have the Blower Motor amp issue on a 2003 pathfinder.
Do you think this info is relevant enough to perform the repair on mine ? :confused:
If not, do you know wher to find similar info for an "03"?

Great post.
Thanks

User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

Welcome to the forum, paulbrev!

Does your blower motor amp look like the one in Ted's '02 Quest (described above)?

Bill S
Posts: 3
Joined: Sun Jul 15, 2012 4:56 pm
Car: 1999 Infiniti I-30t

Post

Have 99' I-30t with failed thermal cutout. Looked up Mouser and part# 447-XYP2BN143-RC and they do not have them anymore. What is chance of buying one from you? I checked resistance and it is open.

Thanks,
Bill S

User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

Bill, this one from Digi-Key should work just fine as a substitute.

Note that Digi-Key likes to tack on a $5 "Minimum Order Fee" on small orders, so you may end up paying quite a bit more than the 74 cent price of the part itself.

Bill S
Posts: 3
Joined: Sun Jul 15, 2012 4:56 pm
Car: 1999 Infiniti I-30t

Post

If you still have Mouser Thermal Cutout part # 447-XYP2BN143-RC I'd like to purchase one from you as Mouser is out of them. You can e-mail me at [email protected].

Thanks,
Bill S

User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

No - as mentioned in some of the earlier posts in this thread, I'm all out of spare parts - and have been for some time.

Bill S
Posts: 3
Joined: Sun Jul 15, 2012 4:56 pm
Car: 1999 Infiniti I-30t

Post

Thanks, I'll get with DigiKey and buy a couple of them. Even with $5 tack on fee cheaper than $148 the dealer wants for a new blower Amplifier. Great article!

User avatar
G8rDuc
Posts: 32
Joined: Tue Nov 27, 2007 8:02 am
Car: 96 Maxima/01 Pathfinder

Post

Love that this thread is still going. Ok, so I have an 01 Pathy with a similar situation but the difference is, my blower motor will come on whenever it wants. When it's not blowing, you can feel a very low force of air coming out of the vents. I'll leave the speed on the highest setting and out of the blue, it will start blowing...then stop at any given time. If I turn the defrost on, it will blow at a low speed...then come on again. It's my understanding from this thread that the amplifier will either work or it won't, so it doesn't sound like it's bad unless it has a contact that just hasn't "blown" completely. I just replaced my fan motor about 4 months ago. Any ideas?

User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

Did it start behaving that way (1.) before you replaced the fan motor, (2.) immediately afterwards, or (3.) only very recently?

OldQ
Posts: 1
Joined: Thu Sep 06, 2012 4:48 pm
Car: 1992 Infiniti Q45
1970 Datsun 240Z

Post

Skibane,

Love your post on this subject and appreciate the clarity and depth with which you explain everything. I really love my 92 Q but my blower fan runs all of the time now and will not shut off. I am desparate to find one of these Darlington Transistors which you describe. If you still have any available for this year or know where else I can get a compatible one I am very interested in getting one immediately. Thanks in advance!

maxnix
Posts: 22628
Joined: Mon Jul 22, 2002 8:11 pm
Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45

Post

This might be your controller panel as they were known to fail. Search the threads. Jerry's in San Diego fixed them for $100. Someone posted a fix, but I bet the pictures are lost.

IslandInfiniti
Posts: 5
Joined: Fri Nov 02, 2012 8:57 am
Car: 2002 I-35

Post

Skibane,

I am new to this site and I found your thread on fixing the FCA very helpful. I have determined that the problem with my FCA is the thermal cutoff. However, finding a replacement part is almost impossible. I have been to multiple websites, including Mouser, and the part is no longer sold. Also, I can not find a cutoff with similar ratings. You mentioned that you have some for sale. May I purchase one from you?

Thanks

IslandInfiniti
Posts: 5
Joined: Fri Nov 02, 2012 8:57 am
Car: 2002 I-35

Post

Skibane,

Disregard my previous post. I read that you are all out. Thanks for the Digikey link. I will use that part.

nice_man_36
Posts: 23
Joined: Tue Nov 06, 2012 6:40 am
Car: maxima 2001 GV full automatic
Location: qatar
Contact:

Post

thanks very much about this subject
this subject will change my mind to change my ac unite control from analog normal one to digital cuaz this fan control one of the important defrant between analog and digital one then i will add digital sensor

but now im looking to this part
many thanks

mcdonald
Posts: 1
Joined: Tue Nov 06, 2012 6:24 pm

Post

hello, I have the 2007 Sentra, its has a problem with the fan control amp too, air keep blowing when the key turn on. i replaced a new fan control amp in it, work fine!! but two weeks later, it does the same thing, air keep blowing when the key turn on, i checked it, the Thermal Cutout look fine, im sure is the Power Transistors go bad, but what can make it go bad??? and can i use the Power Transistors like yours, because its looks same as your Y33, i dont want to spend another $130 for the same thing!! thank you

User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

Welcome to the forums, mcdonald!

If the blower motor is old, it can draw too much current, which overheats the fan control amp.

For this reason (as has been previously mentioned), it's a good idea to replace your blower motor after fixing the fan control amp - or you may have to fix it again.

If your Sentra's fan control amp looks the same as the Q45's, you should be able to use the same replacement transistor as the Q45 uses.

marocano
Posts: 1
Joined: Tue Dec 04, 2012 3:11 am
Car: scenic 2 1.9 Dci Luxe privilege

Post

Hi everybody. The FDH5500 component is obsoletbut you could still find it on ebay.com or stores like http://www.irfp064n.com.
I think this component is equivalent to irfp064n or STW80NF08-55 or HUF75344G3.
Do not forget to verify and clean water drain circuit because when dust block water, fan would be touched and make it drive much power.

regards.

lacibacs13
Posts: 1
Joined: Thu Dec 06, 2012 9:51 am
Car: Nissan Primera P12

Post

Skibane: I measure aroud 6.5 Volts or so on pin 34 if the blower is turned on at ANY speed. I changed both the Mosfet and the thermal cutout and thy seem to be fine not. But if installed, the blower runs on full speed, no matter if it's ON, OFF or not on full speed. Any ideas?

Thanks!

Laszlo

User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

lacibacs13 wrote:Skibane: I measure aroud 6.5 Volts or so on pin 34 if the blower is turned on at ANY speed.
Does it still measure around 6.5 volts with the system turned completely off?

(BTW, welcome to the forums!)

GN1220
Posts: 1
Joined: Sat Dec 22, 2012 9:10 pm

Post

I just found this site and your thread regarding the FCA fix. I'm working on my Father-in-law's 1993 Maxima and I need to verify which parts I need to repair his FCA. If the components are no longer available can someone tell me where to get a new FCA? Hate to spend a ton of money but I don't want to mess with this for weeks either. Thanks, Mike

User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

GN1220 wrote:I just found this site and your thread regarding the FCA fix. I'm working on my Father-in-law's 1993 Maxima and I need to verify which parts I need to repair his FCA. If the components are no longer available can someone tell me where to get a new FCA? Hate to spend a ton of money but I don't want to mess with this for weeks either. Thanks, Mike
On page 3 of this thread, Rayme747 reported that a new 2SD1297 transistor fixed the FCA in his 9'2 Maxima, and that Audiolab of Georgia is still selling this transistor. As of right now, their website is showing 19 of 'em in stock at 4 bucks apiece (link here).

If I was you, I would:

1. Measure the resistance (ohms) of the thermal cutout in your existing FCA to confirm that the thermal cutout hasn't opened up. You can do that without disassembling the FCA - the instructions are described in my first post on the first page of this thread, but are also repeated here:

Image

2. If the thermal cutout is still good (i.e., isn't measuring infinite ohms), then I'd disassemble the FCA to confirm that it has a 2SD1297 inside - If so, I'd order one from Audiolab of GA. Four bucks (plus a little for shipping) for the transistor is dirt-cheap, compared the cost of replacing the entire FCA.

VidraScuba
Posts: 1
Joined: Wed Feb 20, 2013 4:42 pm

Post

Can you tell me where to find one of ( Mouser Part No. 447-XYP2BN143-RC) thermal cutouts. I have tried and cant find it anywhere. Maybe, you can suggest substitute, or if you still have some, I would buy it of you.
Thanks

User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

VidraScuba wrote:Can you tell me where to find one of ( Mouser Part No. 447-XYP2BN143-RC) thermal cutouts. I have tried and cant find it anywhere. Maybe, you can suggest substitute, or if you still have some, I would buy it of you.
Thanks
A substitute has already been suggested in this thread, 18 posts above yours.

:slap:

tks_Nico
Posts: 2
Joined: Sun Feb 19, 2012 8:33 pm
Car: 2001 Pathfinder

Post

Hi Skibane. Just wanted to say thank you for the great write up.
With the help of your article I just finished repairing my Y-33 version ( 2001 pathfinder ) Fan control amplifier. From tear down to having it all put back together took about 1.25 hours for me.
Obtaining FDH5500_F085 was not a problem, Mouser had over 300 in stock ( $3.82 ), Digikey and Arrow also had over 300 each in stock. USPS delivery took about 3 days. Although I didn't need a multi meter, I did meter both the old and new Mosfets. No surprises, the old one was shorted between the Drain-Gate-Source. The new one was over a megohm in all directions.

So thanks again for taking the time to write this up, take pictures and post the results. Your efforts saved me about $250 bucks. My wife was so happy she said she'd take me out to dinner ;)

User avatar
Skibane
Posts: 1056
Joined: Wed Apr 26, 2006 5:33 pm
Car: 2000 Q45 AE 110K
Location: San Antonio, TX

Post

Kewl. :cool:

Thanks for taking the time to post your results, and welcome to the forums!

User avatar
burgy240
Posts: 573
Joined: Sun Jan 05, 2003 4:44 pm
Car: 2000 Q45 Ann. Edition Blk on Blk
Location: Florida
Contact:

Post

Thank you for the great write up. As I am busy with work (excuse) and not sure of my own soldering ability (truth) I decided to go to the JY and find a replacement for 2 bucks. I found it out of a 95 Maxima with, of course, auto climate control. It plugged right in and works fine so far. I wouldn't have know or tried it without this thread though so thank you! Now if I can find the materials I can take the chance of fixing my original one and if I screw up....oh well. Thanks


Return to “Q45 Forum / Cima Forum”