wavesonic

Hi All,

In my recent diagnose on an intermittent AC issue, I came across this thread and ran an AC self-diagnostics test on my 05 LS430:
https://www.clublexus.com/forums/ls-...ditioning.html

I am getting error code 21, 24, 34, and 35.

By reading the above thread, it looks like 21+24 is normal. But what do error codes 34, 35 mean? It wasn't documented in the above list. Any help would be greatly appreciated!

rkw77080

Here are the pages from the repair manual regarding DTC 34 and 35. Hope they are helpful...

wavesonic

Thanks for the info. I will remove the servo motor and have a look!

legend921

Where are the servo motors located? I have the same codes. 21,24,28 34,35. Didn't think I would have errors since my AC system works just fine but I wanted to check and surprised that all of these codes popped up. Could you take pictures?

Thanks

wavesonic

So I've connected TechStream to the car, and it is listed the 34, 35 as historic error and not current. I didn't pay much attention to it. Instead, I replace the AC high-pressure sensor switch 2 days ago and AC has been working reliably so far.

Also cleared the DTCs, and haven't seen 34, and 35 come back.

legend921

Hmmm, thanks for the update. I may need to reset it using techstream as well. I did all the self diagnostics and both sides will blow different temps when set and all other motors work. The only thing is mine always runs on recirculate when in Auto. It never seems to switch to fresh air even when driving in open roads. I have also cleaned the Smog Sensor but the system still remains in recirculate. I prefer to get fresh air over recirculate when ever I can but since the car has an auto feature, I would like for it to switch itself and ensure that everything is working 100 percent. Anyone here have any other methods of checking the Smog Sensor?

Thanks.

Tom57

It's not only the smog sensor that opens and closes outside air. The Auto Recirculate is governed by temp and humidity sensors inside the vehicle. Run the A/C for awhile in Auto, after the temp & humidity in the vehicle has been reduced, the system should switch to outside air.

legend921

Tom57, thanks for the additional info. I definitely run the A/C as my commute in the car is about an hour drive each way. It has never changed for me. Even when I took the car on a 3 hour drive to Philly, never changed once with the A/C set on Auto the entire time. The only time I have seen it change was when I moved the temp to 82 from 76 and it changed but when I changed it back down to 76 and back up again shortly after the first time I saw it. It didn't change at all. I do enjoy the A/C system but prefer it to switch to Fresh Air from time to time and don't know if something may not be working 100 percent regarding to the sensors.

Tom57

Cold weather same? If so, then it's probably a sensor. The fact that it does change to outside air when you raise the temp setting would seem to point to an in-cabin sensor.

legend921

Yeah, it just stays in the recirculate mode. I don't know if it could be the in temp sensor since it does adjust the A/C temp and Fan Speed accordingly. I keep suspecting the Smog Sensor since the car was originally from Southern California where there is a lot of smog and high heat temps. It was super dirty when I cleaned it so I don't know if something may have affected the sensor.

Tom57

By raising the temp control to 82* and then it auto switches to outside air is distinct from the smog sensor though.

Edit: "Cleaning" the smog sensor is only rinsing the white filter, not the actual element that detects 'smog."

legend921

Yeah, I cleaned the filter and just use an alcohol swab on the circuitry to clean any area that I couldn't get to. Changing it up to that temperature to 82 only happened once when I noticed that it flipped from recirculate to fresh air. It has never done it again since then. I even lowered the sensitivity of the smog sensor in the car. I don't know what else it could be. What other sensors could possibly determine recirc and fresh air itself? All other actuators and servos work as it should since it does change the Air Mix and it all adjust accordingly. The rear air comes on when it needs to as well as turn off when it needs to if that helps. Don't know if having the extra system may make the A/C system perform differently.