usdmls400

Sup club lexus members, i recently encountered a problem with my ucf20, no matter what speed i put the fan on, it doesnt come on, checked all my fuses and relays, theyre all good, even bought new relays just to see if that was the problem, but it wasnt. I ran the codes thru the ac command screen using the 'auto' and 'recirculate' buttons on my ac panel, returned codes 21,24. I know the vents and my condenser are still working cause i feel hot air, or cold air slowly creep thru the vents when i change the temp or put the ac on while im driving, I know the blower motor resistor could be bad and im really trying to see if thats the problem before i dump 270$ on a stupid part. If anyone can help i would much appreciate it.

LScowboyLS

the blower motor control module (aka blower resistor pack) p/n 87165-50020 is the most common suspect, and by the way, get the real part from an online Lexus dealership such as Sewell Lexus using our Club Lexus discount or Lexus of South Atlanta Parts or Lexus Parts Now, because the price will about $70-$80 cheaper than Autozone/Advance/O'Reilly/Rock Auto on some aftermarket junky one. (real Toyota part about $200 or less)

this is one of those rare cases where aftermarket price and discount online dealership prices are reversed!

as far as a way to test it, there is a procedure in the factory service manual, although the easiest way is to temporarily swap out yours with a buddy who has a 95-97 LS400

usdmls400

Thanks man.

LScowboyLS

If you find that your blower control module is indeed the problem, and it likely is, I am interested in obtaining your old one, for testing purposes, so I can develop a low cost DIY repair for folks in the future! (similar to my DIY ECU capacitor fix)

PS - here is the lowest price in the country on the real genuine Lexus part brand new - $187

YoshiMan

I would check the voltage and also hook a 12v feed to the blower motor just to double check, since the control module is a bit on the pricey side.

I had the brushes in my 89' 4Runners blower motor just plain wear out, but its got close to 285k on it now as well.

LScowboyLS

this is always a smart plan!

although I have yet to ever hear of a blower motor going out on an LS400, doesn't take long to do a quick check with a spare battery!

Yamae

You have to be careful that the blower control module is sometimes killed by the worn blower motor. A new blower control module will be killed again before the fuse opens due to the reason that the break down is caused not by the current but the di/dt or in other words the fly-back energy. We'd better to check both the voltage and the current before replacing the module.

YoshiMan

Another small check that works sometimes, like in the case of my 4Runner when its motor was dying, is turn the fan speed up and then give a few quick taps to the bottom of the motor housing.

As funny as it sounds, if the motor fires right up afterwards that means its definitely on its way out, as it didn't have enough electrical contact to start itself up, but a little tap might jostle the worn brushes enough to make a connection for a moment.

If that doesn't work, then do what Cowboy said and test her out!

LScowboyLS

more great advice from Yamae and Yoshiman!

the whacking it with a dead blow hammer (a safe type of hammer for this) trick also works on starters, on cars where you can get to them (not ours! )

timmy0tool

iTrader: (7)

i was about to say, i don't see anywhere under our dash that you can give the fan a good whack. it's buried inside the dash!

Mountain78

I purchased a new one from Lexus of Atlanta.....it didn't fix the problem but I couldn't return it.
so I have the used one.....it looks like new

usdmls400

so, the new resistor came, and i plugged it in. sure enough it didn't work as i would have expected. but oh well. any other ideas :|

LScowboyLS

have you put 12V directly from a battery to the blower motor as some of us suggested earlier, and have you also MADE SURE every fuse and relay inside the car and under the hood is in good working order?

usdmls400

everythings good ill prob just replace the motor now, if that doesnt fix it oh well lmao

LScowboyLS

if 12V applied directly to the motor turns it on and it blows fine, then replacing it is not going to solve anything, because it is in fact good if it blows with direct battery voltage and does not need a whack to get started

just make sure to take a good long look at the wiring diagram and know for sure to what pins on what connector you are applying the 12V and what polarity!
(you want to closest connector to the motor itself, the first connector in line electrically, when tracing the circuit back, will be very physically close, like inches)

it can get expensive to just be a parts changer, do a bit of troubleshooting and isolate the defective part before ordering!