I have the 'Replace AC Filter' message on now so ordered a new front cabin filter from Amazon. I decided to look into the rear AC filter at the same time and find they are priced between about $90 to about $240! Wow. Has anyone ever replaced this filter? If anyone can find a better price I would appreciate knowing where. I will take the existing rear filter out for an inspection when the new front AC filter arrives from Amazon.

 

yes i replaced mine and I sure as heck didn't buy OEM. I must have found an equivalent, there a bunch of companies out there, one does a lot of videos on youtube for filters.
anyway no issues with non OEM and its been several years.

 

I've found the rear A/C filter to have a rather long life. It's a large filter and is not subjected to outside air, just the ambient air inside the car. The UV light cleans up bacteria, etc, and doesn't have to deal with mold, etc. Take it out and inspect it. I don't think you'll see a lot of dust on and embedded in the filter. The carbon color will start turning to a lighter color. You could vacuum and blow compressed air thru and then make a decision as to whether you need a new one or not.

 

Beck Arnley 042-2109 is a lower-cost aftermarket substitute for the rear filter. The 2001-2003 Lexus part number is 88508-30110, 2004-2006 part number 88508-50080. I am pretty sure there are no differences in the fit, dimensions, or build quality between the two different Lexus part numbers, but if anyone knows otherwise, please chime in.

I also agree that the rear filter has a very long life. The rear filter is only used when your rear fans are on low or high. If your rear system is set to auto, and the rear fan is off, the rear filter is not used at all. When you need your coolbox to get cold quick, set rear AC = ON and rear fan = HIGH. When you need your cabin air extra clean, turn the rear fan on HIGH, and the giant rear filter combined with the UV light will give your cabin air a super cleaning.

You could also light up a cigarette to trip the smoke sensor, and the rear system in auto mode should adjust itself accordingly. I don't smoke and wouldn't smoke inside an LS430, but I do know that TechStream and the service manuals show a smoke sensor connected to the rear AC system.

 

When the rear system is set to Auto, it is completely automatic. If you turn the fans off, it is not in automatic mode. I leave my rear system on auto at all times. Sometime rear passengers will monkey with the controls. They have complete control at that time. When they change the temperature, it overrided and changes the driver/front passenger settings. This is because the Lexus philosophy was that the rear passenger in the UL was basically being driven by a chaffeur and he was in command. Interesting in the difference in Japanese philosophy. The ES models are Executive Sedans and named as such because they didn't believe that Executives should drive the LS (Luxury Sedan). Too bad that we (the US) don't share that humility and care for the common people.

 

Stan, thanks for the Beck Arnley 042-2109 part number. I see it can be had for $34 from ebay seller. That seems a reasonable price to me.

The front cabin filter is suppose to arrive today so I will replace that one and have a look at the rear filter while I have the car.

 

I replaced the front cabin filter today and reset the maintenance required message. Pulled the rear cabin filter and it looked like brand new except for a little discoloration on the bottom side. I think the UV lamp is underneath the filter so that makes sense. I am leaving the rear filter alone for now.