salimshah

I replaced mine as the display would show different speed but the blower would not kick up. Giving full B+ (12v) the fan ran full speed. I was pretty sure there is no issue with connectors and wires.

If you want to further diagnose get the wiring diagram and measure the control voltage to the controller module as you adjust the fan speed with the **** and see it go progressively higher. If the output voltage from the module does not change with the control voltage your module is bad. Make sure you do get B+ 12v from the battery on the secondary side.

You may like to look at used part. Part is not hermetically sealed so make sure it has not been sitting out in the rain.

Salim

rmk9785e

Very helpful indeed.
A Youtube video at was very helpful in removing the glove compartment and accessing the control unit.
Removed the Blower Control Module. Looked inside. There is no user serviceable part in there so have to replace it. Found a new one at eBay for $142.87. The part number on my Blower Control Module is 87165-22040 but it seems to have been superseded by 87165-22050.
Found testing instructions in the attached document uploaded by GuyTelefunken on a different thread. Here are my readings: The first image shows probes on S1 and vehicle Ground. With the engine running and blower at high speed, the voltage is about 1.3V which is in range specified in the document. That tells me the A/C control is sending the correct signal. (Interestingly, if I lower the blower speed from the ****, this signal voltage goes up to 9V but the document doesn't ask for it so it can be ignored.)



The second image is with probes on M+ and M- of the Blower Control Unit. When the blower runs, the voltage varies between 6 and 12 V depending upon the fan speed displayed on console. When it stops, the voltages goes down to zero.



These readings confirm what Salim has so wisely advised. It also confirms that the blower motor runs fine as long as it gets the required voltage. I've ordered the module and will update with the results.

This forum is a wonderful resource.

matts6887

I am starting to think that i may need to take a look at my air mix servo because a lot of times; even when the climate control airflow indicator is pointing to the floor to where warm heated air is supposed to come out; sometimes its cold air instead and sometimes it seems like i need to crank the temp up quite a bit to get the air to be warm. And yes we do have winter days here in AZ where it can be cool and rainy etc.

sugzz

iTrader: (9)

Hey guys, sorry to bump an old thread but Im having the same issue with my 99 RX300. My blower motor would work for a few minutes then turn off. Now its not turning on at all.I purchased a blower motor control thinking that would fix it, however I'm still stuck without it. I took the fan out and connected directly to a battery and it worked. Tonight I checked the wiring from the control, my SI location is getting full 12v. If I place a ground on it the fan kicks on at full speed. I know its only suppose to get 1-3 volts depending on speed. I'm not sure what else to check. Please help.

maxSteel

It sounds like you are failing the blower motor relay test in that blower.pdf file

sugzz

iTrader: (9)

Thanks for replying. Does anyone know where the blower motor relay is located? The funny thing is I can hear the relay clicking when I turn on the climate control.

maxSteel

That blower.pdf file has a drawing that shows where it is

salimshah

See post #14 of this thread.

Salim

sugzz

iTrader: (9)

Thanks guys but as I mentioned, I already changed that part that is in shown in the pdf file. My question is is there another relay?

salimshah

Monitor the voltage on the input side of the controller and see it change the output side on the controller pins and then on the fan-motor.

Salim