What is the company that makes the cabin air filters on the 2005 LS430?

is it ACM?

 

I suspect that the filter is made by Denso as they make the OEM engine air filter. I was just looking at the Kragen Auto Parts site (www.kragen.com) and they list an after market filter from Purolator if you wanted to by an aftermarket product.

 

I just checked in my wife's '04 LS430 and it is indeed a Denso filter. It's pretty easy to replace.

I did the following steps
1) empty the glove box
2) remove the shelf in the glove box by lifting (wriggling) the vertical support and then sliding out the horizontal arm. It's held in by a tongued piece of plastic that slides into a groove in the glove box.
3) you'll then see a door with two releases (press down on the "latch") and the door fold toward you and then will lift out.
4) you now have access to the AC filter. The door is held in place by two latches on the bottom of the door (press up on the latch - I used my finger (palm facing up)). You find the latches by locating the 1/4" round piece of plastic under each latch. The door falls out to the bottom.
5) slide out the filter and filter tray by pulling on the tray handle (the tray and filter are labeled "up" so you should be able to easily reassemble them).

I took some photos and I'll add them shortly.

 

To reset the "Replace A/C Filter" message, start the car up and after getting the "Replace A/C Filter" message, press and hold the A/C off button (for about 4 seconds) until you get a "A/C Filter Reset" message.