QX4ME wrote: ↑

Sun Jul 29, 2018 2:09 pm

I replaced the failed fan blower motor resistor module in my 02 QX4 bought from eBay. It worked normal but lasted me only one day. It is not a genuine Nissan part, no part number on the module and only $16. I will buy a genuine one.

B

Whether it is OEM or aftermarket shouldn't matter. That thing is nothing but a giant ceramic heat sink and the only spec that matters in this case is how many watts it is rated at. You just have to ensure you're replacing that unit with one rated at the same value. I would double check on the wattage of the original and the one you replaced.

The original FET is FDH5500 (Fairchild), almost obsolete. The FET I use now is CSD18536KCS (Texas Instruments).
Both have max power dissipation of 375 W. Stock FET continuous current is 75A and my FET is 200A.

Thermal resistance from junction to ambient: stock is 30C/W, mine is 62C/W because of its smaller package, which is the only thing I worry a bit. for now I just want to try to make it work.

I agree OEM and aftermarket should be the same. Maybe I just got unlucky with the eBay unit that only lasted one day. The OEM lasted me 16 years.

This has been an issue since new -- I'm sure this thread being so old that I chimed in at some point. IMO -- buy the OE part for $100 and be finished with the problem. The aftermarket have a history of failure ...like many aftermarket electrical items.

The Denso cabin filters are cheap and fit the best ...

I just tried with two modules both using my own FET, with a different sensitivity setups.The more sensitive one worked 50%; it can only turn off fan when at max speed, or can only reduce to min speed. Not good. The other one just failed immediately. I am totally lost. I think I need to give up.

Yes, I will probably have to buy an OEM.

I just experienced the same thing: Got a really great deal on eBay on an aftermarket amp, and it worked for two days. Ugh.

If there's something else we're doing wrong, please, someone, let us know.

Recap: Blower suddenly wouldn't shut off--stuck on high speed no matter what (A/C, Econ, Off). Installed aftermarket amp = fixed. (Yay)

Next day broken again (after hitting a bump in the road?). Interestingly, next time we started the kicked it was "fixed" again. 2nd day, however, stuck on high again.

FYI, I removed the two 15-amp fuses until I repaired it. It really is loud otherwise.

Thanks for keeping this thread alive!

QX4ME wrote: ↑

Thu Aug 02, 2018 7:19 am

I just tried with two modules both using my own FET, with a different sensitivity setups.The more sensitive one worked 50%; it can only turn off fan when at max speed, or can only reduce to min speed. Not good. The other one just failed immediately. I am totally lost. I think I need to give up.

Yes, I will probably have to buy an OEM.

Did you get the OEM part, and has the problem been solved "for good"?

I, too, sort of gave up once the aftermarket solution failed (on the second day for me). I have not, however, moved forward since. (As I mentioned, I simply pulled the blower's two 15A fuses for now.) The seasons are changing, however, and we're gonna need that heater soon.

Thanks, everyone, for any and all direction and experience!

Jack

buy the OE ... the extra cost to go aftermarket will be whatever they change you. Because, you will be be buying the OE shortly after. It's amazing to me that there is a thread this long and old -- explaining the proper way to go and people still don't follow it.

Most aftermarket electrical parts are junk -- it's just the way it is. Throughout all makes -- buy the OE as cheap as possible. Fixed.

Treepreacher wrote: ↑

Sat Sep 22, 2018 6:23 pm

QX4ME wrote: ↑

Thu Aug 02, 2018 7:19 am

I just tried with two modules both using my own FET, with a different sensitivity setups.The more sensitive one worked 50%; it can only turn off fan when at max speed, or can only reduce to min speed. Not good. The other one just failed immediately. I am totally lost. I think I need to give up.

Yes, I will probably have to buy an OEM.

Did you get the OEM part, and has the problem been solved "for good"?

I, too, sort of gave up once the aftermarket solution failed (on the second day for me). I have not, however, moved forward since. (As I mentioned, I simply pulled the blower's two 15A fuses for now.) The seasons are changing, however, and we're gonna need that heater soon.

Thanks, everyone, for any and all direction and experience!

Jack

I bought another cheap module from AM Autoparts, not OEM. It has been working fine from mid August, not long enough to tell reliable or not. Every time when I use A/C, I purposely tried turning it off from max speed, min speed or in between; it works fine.

They don't hold up ... I can see trying options if the part was horribly expensive ... but for 100 bucks it's over and done with. Having one work for a couple months is not fixing the problem.


I get that they are only $20 bucks

A BIG thanks to everyone on this string. Owing to the excellent advice here, I was able to repair my blower for $5.00
I went to a local junkyard, located a Pathfinder and someone had already taken the dashboard off and the blower amp was sitting right there
I paid $5.00 for it (including the entrance fee), went home and swapped it out, and it turned right on. I also discovered that my 98 Pathfinder LE has the cabin filters -- and... that they hadn't been changed in 16 years! They were filthy. I replaced them and cleaned out the vents and the blower/AC is working so well now.
Thanks again everyone!

It's been near one year since my cheap module was installed. It is still working fine.

QX4ME wrote: ↑

Tue Aug 06, 2019 6:31 pm

It's been near one year since my cheap module was installed. It is still working fine.

It's waiting -- for that special hot or cold day .. when you need it the most --- far from home.

Sincere thank you to everyone wh posted, Andrew your fan amp steps fixed mine just exactly as you described, thank you kind sir. I have a 99 qx4 with 310k miles, ac works fine again here in florida, need to wait to test heat but should be fine. I did hit a snag when trying to replace filters, no slot to remove or insert new ones. debating on whether i want to invest time to cut that thick plastic or drive it like it is. (lasted 23 years so far).

Regardless, i sure appreciate everyone's detailed posts. Andrew YOU ROCK ! !

tookaflyer wrote: ↑

Fri Oct 28, 2022 3:49 pm

... I did hit a snag when trying to replace filters, no slot to remove or insert new ones. debating on whether i want to invest time to cut that thick plastic or drive it like it is. (lasted 23 years so far).

Cutting out the slot blanks in the air box to install cabin air filters is kind or easy. The box was actually made to be cut open easily. The only thick portion of plastic is where the top and bottom box halves come together. Because of the way the blanks were molded into the box, there is a natural edge, about the width of a razor knife blade, that makes for a perfect cut to be followed straight and true. At the top and bottom of the two blanks I cut out when I opened mine, I simply poked the tip of the blade through the plastic and made these half inch horizontal cuts up to the vertical cuts I had already made. You will be left with a thicker rib in the middle of the opened slots, which is where the two halves of the clam shell air box come together. This small thicker section is a bit tougher to cut with the razor knife but it can be done, slowly and carefully. A hacksaw blade on that piece would be quicker. At this point, you now have a stock OEM air box ready for the filters to be installed. All the form, fit, and functional features for the cabin air filters are molded into the air box on the outside and guide slide slots for the filters are on the inside, hiding all these years, waiting to be put to use. All you have to do is cut away the blanks and the center piece to make one tall slot opening for the two filters to be installed.

Your post on the blower motor resistor and more regarding the qx4 is very helpful.

I’m hoping you can point me in the right direction. My QX4 is a 2001 with 142k mi. I’m pretty sure I have changed the blower motor fan assembly and resistor in the last 8 years (I think when I first got it about 8years ago).

Facts:
All winter I could only feel heat coming out of the vents if I was driving but at idle/stop the vents blew cold even when on max heat. I thought a vent was stuck open.

On the hottest day of summer so far, I was sitting at idle in a parking lot and nothing happened (no noise, pop, or mechanical sounding failure) except my vents quit producing air but the seepage of air when on ECON was still cold.

I changed out the blower motor resistor and tried with old blower motor fan assembly

I changed out the blower motor fan assembly and tried new one with new resistor

Tried new blower motor fan assembly with old blower motor resistor

Hooked old blower motor fan assembly to a battery and it’s good.

I exchanged the relay with another of the same specifications but still no air

I put new in cabin air filters in and saw a lot of leaves m/debris down there and tried to knock it out.

Next I took it to Midas and had them try all the new parts and all the old parts in each combination of each other.

Still no air coming out of the vents. They recommended i take it to an electric place.

I hear the compressor kick on and off. The air seepage is still cold.

Took it to an Infiniti dealership and told them all of this. They sent me back a diag and $650 invoice saying it’s the blower motor resistor. I told them they need to find a different diag.

I have not authorized them to proceed because both myself and a Midas have trouble shot the resistor so that doesn’t appear to be the issue.

Observation:
This vehicle has always been loud at start up and squeals when I turn the ignition

Thought it was the belt but had it replaced but the sound persisted.

Recently I added coolant the squeal went away
I have been to several shops and now the dealership and endless hours troubleshooting myself but no one can seem to diag this.

Any advice?

I guess my only thought is perhaps the resistor I got was bad so I tested everything with two bad resistors but it looked new in comparison and identical in specifications to what was already in the vehicle.

The blower circuit isn't mysterious. Blue at the blower motor should have 12V, if it doesn't then there's an upstream power issue. Blue/White at the blower should also show 12V with the blower off, and a lower voltage with the blower on. If it shows 0V when off then the motor is shot (bad commutators or brushes). If it shows 0V or a middle voltage when on but isn't spinning, that also means the blower is bad. Blue/White at the VBC (resistor) should show the same voltage as it does at the motor, if not there's a broken wire. If that all checks good, with the blower on, Black at the VBC should show near 0V. If it shows a higher voltage then your ground wire is bad. If that checks, monitor Blue/Yellow at the VBC while changing the speed settings. You should see a voltage that rises and falls with the speed setting, if not there's a problem in Blue/Yellow or your control head is bad. If the signal moves normally then the VBC is shot.

Thank you to all on this forum! I was able to find out that the original blower motor resistor sold to me by O’Reillys was bad. Napa sold me a good one and we are off the the races. I appreciate the input of all!