Fan Blower 92 Ls400

[Alexander the o.k.]

Hey Guys,

Did a search for blower speed, blower resistor, blower relay, etc. but every post just dances around the issue.

The issue:

Low and Medium speeds are gone. The low speed went 1st. Then yesterday medium didn't work. I never use high til now since it sounds like a 747 at full throttle. But when the heat index is 115*, what the heck, right? I always use max cool, manual. Never auto. Tried auto when medium speed died, and it did nothing.

Anyway, does this sound like a relay, or is it called a resistor, or the motor itself? I will check the fuse, but if it's the fuse then there should be no juice at all, right?

If it's a resistor, can I use a Yoda part?

What is a good source for lex aftermarket parts?

[jcrome04]

Have you ever changed your cabin air filter? Does yours have one?

I've heard of heavily soiled cabin air filters restricting the air to the point the driver thought the lower fan speeds were not working.

[Alexander the o.k.]

Hey J and thanks for the quick reply.

I'm pretty sure there is no ac filter in the 92. I will check the manual tho.

If it were the filter, wouldn't that happen gradually instead of boom----gone?

I will search the forum for glove box removal tips as that is where the blower is located, I would guess.

Where is the resistor, or relay or both?

Could they be mounted on the blower?

[jcrome04]

Sorry don't know TOO many exact details about the 1st gen anymore. If it does have an "in cabin" air filter it whould be behind a removable panel on the back of the glove box when open. No need to completely remove it.. It is possible that's an option not added until series II (93-94).

The fuses or relays would probably be under the hood, but they don't have separate fuses for each fan setting.

Just trying to think of the cheapest route to check first!

[wwest]

Hey Guys,

Did a search for blower speed, blower resistor, blower relay, etc. but every post just dances around the issue.

The issue:

Low and Medium speeds are gone. The low speed went 1st. Then yesterday medium didn't work. I never use high til now since it sounds like a 747 at full throttle. But when the heat index is 115*, what the heck, right? I always use max cool, manual. Never auto. Tried auto when medium speed died, and it did nothing.

Anyway, does this sound like a relay, or is it called a resistor, or the motor itself? I will check the fuse, but if it's the fuse then there should be no juice at all, right?

If it's a resistor, can I use a Yoda part?

What is a good source for lex aftermarket parts?

Your '92 LS400 uses a transistor for controlling all(***) speeds by full HIGH speed, in that case a relay is used to bypass the even the small level of voltage the transistor would drop. With only 12 volts every little bit counts.

Your solid state blower speed control has failed or actually more likely only the final power transistor itself.

"You" can manually only select three blower speeds, the solid state blower speed controller can set ~256 speeds.

[Alexander the o.k.]

Hey J and W,

Thanks both for the replies. We'll get this puppy sorted out I'm sure. The temp was about 100* today, and the heat index (whatever that is) was around 112, i think.

I'm covered with sweat just thinking about fixing this, but I'll be dam*%d if I'll pay Lexus their rates.

Anyway, I think it's narrowed to the resistor or i guess the transistor. But where is it? Where do I buy one? I'll do another search but I may need some pics...

I've seen the term ECU somewhere. Is this the same thing?

What would cause it to burn up?

Thnx guys.

[Alexander the o.k.]

Well, still no luck with the search function for : Aircon transistor or transistor.

I remember seeing somewhere that it might be located on the evaporator. Is this correct?

What steps are needed to replace it so the blower works at low and medium speeds?

[Alexander the o.k.]

Seek and you'll find.

This is a diagram straight from lexus of the blower assmbly. Hope it helps others.

The crude arrow is pointing to the transistor, I believe.

[chilkoot]

wwest sounds right on.

I had the same problem in my Taurus, recurring problem of only hi fan blower speed would work. Turned out there was a leak in the windshield that dripped onto the fan speed resistor board and fried a series of replacement boards, each time same symptoms.

High was full unregulated voltage and never went through the fried board, so as only the lower speeds ran through the resistors, only the resisted speeds were cut off when the board fried.

side note, some water got inside of my blower motor and caused some corrosion. it sounded like a cricket was living inside of my AC ducts.

[wwest]

In the parts breakdown picture provided above the power transistor might be represented by part # 88630A, shown "removed" and just to the right of the squirrel cage blower, air mover, part. The power transistor is mounted on the passnger kickwell side of the evaporator plenum case, to the left of the fresh/recirc/blower/blower motor case, normally unseen in the pictorial.

[Alexander the o.k.]

Thanks once again Wwest.

The part circled #87138c was what seemed to be indicated by the Lexus parts guy. That is why I drew the arrow and made the comment on it.

You have just saved me a load of frustration I'm sure.

Cheers!

[Jim Van]

Thanks once again Wwest.

The part circled #87138c was what seemed to be indicated by the Lexus parts guy. That is why I drew the arrow and made the comment on it.

You have just saved me a load of frustration I'm sure.

Cheers!

Alexander, did the power transistor fix your problem? Having the exact same problem and Lexus wants over $150.00 for the part. Where did you get your part and if don't mind, how much did you pay? Also do you still have the diagram that you posted on 9 Jun 08.

Thanks,

Jim

[Alexander the o.k.]

Hey Jim,

Since I lost my job during that time, I have been unable to pursue it. What was interesting to note, is just recently when outside temps were in the 70's I believe, the med and low started working again! I pulled the AC codes and got a 13, which is: 13 ................. Evaporator Temperature Sensor Circuit. So my guess is the temp sensor controls the variable speed fan resistor.

I think the lower ambient temps fell below the sensor's parameters and 'tricked' it into closing.

Still, no use having AC that only works when it's cool out.

It will still require tearing apart the dash to get at it.

Pull your AC codes to get a better idea of what's really wrong.

By the way, I grew up and was a Surfer Dude in VA Bch, and used to drive thru Hamton Roads all the time on the way to see my GF and go to Busch Gardens.

Good luck.

http://us.lexusownersclub.com/forums/index...?showtopic=3794

Thanks again SK!!!

Edit*

Here ya go;

http://us.lexusownersclub.com/forums/index...st&id=10513

Removal:

http://us.lexusownersclub.com/forums/index...st&id=10514

[Jim Van]

Alexander,

Thank you, only get code 21, was told by Lexus that means the A/C control assembly is the fault, bought one off ebay and still has the same problem. Again Lexus pulled out its problem matrix and said ok, guess I was wrong on that one, try the power transistor and by golly for 170 dollars he could get me one.....might wait now till it cools down some and see if all starts working again maybe the Evaporator Temperature Sensor Circuit is cheaper. The good news is given it has been in the high 90's having the A/C blow on high all the time is not a bad thing.

Jim

[Alexander the o.k.]

I wouldn't rush out and buy any more parts until we you get a little closer to the actual problem. ;)

A code 21 = Solar Sensor Circuit which you don't have. So.... maybe run the diagnostic again and double check. Do it in bright sunlight, cause if you actually do have a solar sensor, it will give that code if you run it in shade or at night. I think solar sensors came only in 2nd gens' and not our 1st gen cars (90-94).

Someone clarify this.

[Alexander the o.k.]

Alexander,

Thank you, only get code 21, was told by Lexus that means the A/C control assembly is the fault... Again Lexus pulled out its problem matrix and said ok, guess I was wrong on that one, try the power transistor...

Are you sure it's not just a guy masquerading as a Lexus tech with a fake uniform ?

Seriously, I'd look for a diff dealer quick, before they put you through the well known, very slow, and incredibly expensive 'part you to death' torture.

They're of course holding back on the 'labor cost' you to death sequence of this slow torture until they've more fully sucked you into the routine mentioned above.....

Make no mistake. They are even now, mentally calculating how big your 401k is, and if there is any way to get at it.

Check with a diff dealer and ask if AC code 21 means "power transistor", or as is actually the case, a fan speed resistor.

[python]

how about the blower motor resistor?