Blower fan power is both 12VDC on my 1999 Q45

[IrvingQ45]

Hot summer in Texas, my 1999 Q45 blower fan quit working! User the manual to troubleshoot, Took out the blower fan assembly and put 12VDC on it, it runs good. Check on the power terminal M27 with the key in ACC position, got both 1 and 2 terminal reading to the ground of 12V(Bad but why?). Also measured the continuity between terminal 2 to terminal 35 of the Fan control amp connector M29, it was a few handred K, I thought that is fine. So what is wrong? Need help! Thanks!

IrvingQ45

[goody90q45]

When the fan control amplifier burns up its Darlington resistor the fan will run on high speed only (or is your fan motor not running at all?).

[IrvingQ45]

My fan is not running at all! It runs when I put hot 12VDC to it shell contect but since the power to the contacts are both 12VDC and the blower motor is not running at all... The question is why both of the terminal go to the motor are 12VDC? IrvingQ45

[maxnix]

Look at the wiring diagram in the FSM then reconsider Goody's post.

Your Darlington bridge was taken out by excessive current draw becuase the motor is dirty or failed from wear, or both.

[Skibane]

Isn't the Darlington transistor supposed to ground one of those two terminals in order to complete the circuit to the motor?

I'll bet that you're measuring 12 volts on both terminals because (1.) they're disconnected from the fan when you're measuring them, and (2.) the Darlington transistor that is supposed to ground one terminal is fried.

Replace your dead transistor (and maybe the fan motor while you're at it), and you should be good to go.

[maxnix]

True!

And be sure to tell us from the Infiniti Dealer Performed Service History and other receipts you obtained before purchasing the car how often the cabin air filter had been changed.

You have changed it, right? And the engine intake filter? And all fluids?

http://www.infinitiparstusa.com

[IrvingQ45]

Hi Skibane

Sounds good and thanks for help!

You are right I got both 12VDC when the termical is off from the motor!But I am really do not know where the Darlington transistor located? Where do I get one? How do I know it is bad?

The motor runs fine when I put hot 12VDC on it, I will take it apart to see how bad it is... Thanks again!

IrvingQ45

[IrvingQ45]

Hi Brian

Please let me know where can I get the diagram, what is FSM?

Thanks!

IrvingQ45

[MinisterofDOOM]

Please let me know where can I get the diagram, what is FSM?

FSM is the factory service manual.Here's the section you're looking for:http://www.nicoclub.com/FSM/Q4...a.pdf

[IrvingQ45]

Thanks!

Are we talking about the Fan Control Amplifier? So Do I need to replace that?

Where do I get them? Dealer?

IrvingQ45

[maxnix]

Junk yard like

http://www.car-part.com

if you are feeling lucky or

http://www.infinitipartsusa.com

for new.

But it will fail if you don't R&R your fan motor.

Never heard about those filter changes?

[Skibane]

I just checked my FSM, and for the 2000 Q45, the "fan control amplifier" is actually an N-channel MOSFET transistor (not a Darlington transistor). I'd bet that it's the same for a 1999 Q.

The part we're talking about is circled in red:



It's mounted on the blower housing, located downstream from the blower so that it receives airflow to keep it cool.

What's particularly interesting about this "amplifier" is that N-channel MOSFETs have gotten much better since 1999. Today, you can buy a $3.00 MOSFET from Mouser Electronics that will safely carry more current than any $50 MOSFET available back in 1999.

So, it looks like it should be possible to replace the old MOSFET with a new, much beefier one that would last longer - probably for less than 5 bucks, if you're handy with a soldering iron.

IrvingQ45: I'm one of the baddest MF'ers on the planet with a soldering iron, and have a company account with Mouser Electronics - If you're willing to send me your blower amplifier, I'd be glad to transplant one of the latest, greatest MOSFETs in it - Shouldn't cost more than 5 bucks, plus the cost of shipping the amplifier both ways. If the transplant is successful, I'll do a NICO write-up on how to do it, including photos. If the transplant is not successful, you're only a junk yard away from finding a replacement amplifier. The whole job would take about a week and a half, including shipping time both ways.

What say?

[maxnix]

Damn, I hope mine fails soon (after all it is my wife's car!) and I'll drive down.

[IrvingQ45]

That sounds great but I just afraid that I send it in and it is not the problem at all? I took it out and did some measures and it seems all OK to me? The resistors are measuring good, and the transistor is seem OK too??

Any suggestion?

IrvingQ45

[Skibane]

That sounds great but I just afraid that I send it in and it is not the problem at all? I took it out and did some measures and it seems all OK to me? The resistors are measuring good, and the transistor is seem OK too??

Any suggestion?

IrvingQ45

Best solution would be to test it before replacing the MOSFET - Temporarily install it in my Q, and see if the blower works. If it works, send the unit back (and you'd probably need to start looking for an "Auto Amp" ($$$$$$$$$$$$$$$$$). If it doesn't work, proceed with the transplant.

[IrvingQ45]

Ok, give me your addrss, I will send it.

IrvingQ45

[Skibane]

Very good - I just sent you an e-mail with my mailing address.

[IrvingQ45]

Please respond to my latest email to you..

IrvingQ45

[Skibane]

No e-mail received.

UPDATE 6/18/09: Mike, I still haven't received any e-mails from you. Are you sure you're using my correct address? It should be:

[email protected]
Modified by Skibane at 9:22 PM 6/18/2009

[IrvingQ45]

I send you a couple of emails. And the part is send to you yesterday. If you do not get it today, you should have it tomorrow.

IrvingQ45

[IrvingQ45]

Yes, I replied on your email and you might want to check in the junk mail folder. You should recevied my part today.

IrvingQ45

[ronscarberry]

I was reading an article about how to repair the fan control amplifier on Q45; it looks like the same part from my 1999 QX4; I need the specific tests for the transistor and how to order a new one; the writer of the article said that he had four for sale. I believe they are FDH5500 Moffet transistor. The thermal cut out tested without any resistance so it should be good based upon the article. Is there a cabin filter on the QX4? If so, where is it located; it does not mention it in the owners manual.

Also, the article was great!

[Skibane]

Welcome to the forums, ronscarberry!

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.

[ronscarberry]

Skibane,

Thank you, the numbers on the circuit board are CE-63427 AND 8100064755; the part looks identical to the one in the pictures of your article.

My address is 13031 E Richert Avenue, Sanger, CA 93657; my email is [email protected]

Let me know how much and I will send you the money for the part and shipping.

Thank you for the response.

Ron