The a/c fan speed on my wife's RX300 is very erratic. The fan speed adjusts itself for no reason at all. We can turn the unit on and off and gain some controll but, it always seems to adjust erratically by itself again shortly thereafter. I read in one post that it might be the Blower motor control module or the resistor. Any ideas would be appreciated and also where to locate these patrts on the vehicle.

Thanks:

 

Stupid question, but is it in "auto" mode?

 

It doesn't matter what mode it's in (auto or not) the fan still speed is still erratic.

 

try disconnecting the battery for 5-10 minutes,let everything reset. Do a self diagnostic test on the control first.

 

How do I do a self diagnostic on the control?

 

I think Lexus means see if disconnecting the battery to let things reset to default might correct the problem. In cyberworld, a lot of times that does work. At least it's the FIRST thing to do.

 

Code,actually their is a way to diagnose the a/c,heat computer. If the system detects a problem,it will put up codes on the display. I think you have to turn the key on,pres and hold the auto/and recirc button (at the same time) and it will diagnose itself.As bob hesse would sayretty cool huh?

 

I tried pressing and holding the auto and recirc buttons as you described and nothing happened.

 

It`s on the board here somewhere,I cant find it now.Now wait,try this:
https://www.clublexus.com/forums/rx3...+trouble+codes
Looks like you press and hold as you turn the key on.I did this once,it does work.
Ryan

 

I tried the press and hold then turn key technique and that worked. The only code I got was a 21 "solar sensor circuit" but after reading the posts I concluded that I got that code because I was inside my garage. It's dark outside now so there's no way to verify that there is a problem there. The unit also did a self diagnostic test and everything seemed to check out fine. Any ideas??
Thanks

 

if i`m not mistaken,Code 21 is normal,meaning everything is working as it should(with the electronics anyway).Maybe your fan motor,or relay is going bad.

 

I read in some posts that it might be the resister. Where is the fan motor resister and how would I go about testing it? Or if it's the relay where's the relay?

Thanks

 

It could be the fan resister,I would assume the resister would be by the fan somewhere.