AC won't save the previous setting
12-06-22, 09:19 PM
#16
I had the same issue after replacing my LS460L cabin air filter. As soon as you start the car, AUTO light would come on but no lights on recirc/auto/fresh air button. And the fan would not run and no driver/passenger temp display either. Looked like the whole climate control system was in a shutdown mode. After 15 seconds or so, climate control would come on resetted to 75 degrees and would forget my previous settings when I stopped the car. It was very easily reproduceable every time after I shut down and locked the car. I had not broken the recirc/fresh door infront of the filter as I was very particular about it and read all the instructions before replacing the filter. My fix was to take the filter out of its plastic casing and re-install it with "TOYOTA" "MADE IN USA" and "UP" printed on the filter to face the rear side of casing. Before it was towards the front side of casing. I had noticed it when I took the previous original filter out but did not think it would matter which way the filter goes as long as "UP" is actually pointing "UP". Ironically the car has some sensitive sensors that detect may be the filter is not there I think. I re-installed it correctly and seated it above the blower pressing all four sides. Need skinny hands to get in the back of it. Since then its fixed and climate control works normally as before.
DETAILS: The problem was just as puppo420 described. At startup AUTO climate control light comes on and cannot be turned off, the RECIRC button is not lit at all, the climate system is otherwise not working, no fan, and cannot be operated in any way, no display of temperature selection on either driver or passenger side. Then, after about 1 minute, 15 seconds, the AUTO light cuts off, the NAV screen displays message that A/C is now off, all climate settings have been forgotten, the temperature selection defaults to 75° on both sides of cabin, and climate controls can now be manually operated/set. If the vehicle was only shut-off for a short period of time, the condition did NOT reoccur; if shut-off for a longer period of time, the condition DID reoccur.
When the problem first occurred it had been almost 10 months since the cabin air filter had last been changed/accessed, and the vehicle is a daily driver, so it was unlikely I had damaged the blend door system when I changed out the filter. Further, with the black access cover removed, I could observe the blend door opening and closing correctly when I operated the RECIRC button on and off. In fact, I can't see how someone could even TRY to change the air filter out with the RECIRC button off because, with the blend door closed, there would be absolutely no access to filter's frame/case or its retaining clips unless you were to SERIOUSLY pry open the blend door for access.
I found that the left-side white retaining clip (the clips face inward toward the cabin) on the white air filter frame/case was snugged/clipped-in properly, however the right-side WHITE RETAINING CLIP WAS NOT SNUGGED/CLIPPED-IN PROPERLY. It was a bit loose and so I could make the right-side of the frame/case wiggle up & down a wee bit with one finger. I pulled out the frame/case and the filter was installed in the correct up/down orientation. Though I could not detect any meaningful difference between one end of the filter and the other, I rotated it 180° anyway, ensured it was snugged and positioned well into it frame/case, and reinstalled the frame/case into its position. I ensured both white clips were properly snugged/clipped-in. After that, THE PROBLEM WAS ENTIRELY SOLVED. Just to warn any other mechanic (or such), I put a DYMO label on the black access door warning that RECIRC mode must be on before removal, else expensive repairs will be required.
CONCLUSION: I think the problem was being caused by the one white retaining clip not being fully clipped-down into place. I must have not fully-secured it during the last change and it had wiggled loose over time. There must be some kind of sensor in there that can detect when the air filter is not EXACTLY in place due to clogging or whatever. And if that sensor is 'tripped' then the AUTO button is turned ON and the climate settings are deleted - as a 'warning' that the required cabin air filter is 'missing' and/or needs replacing. And my frame/case was out-of-place just enough due to being unclipped - or was being pushed out-of-place just enough by the blend door when it closed because it was unclipped - to 'trip' the warning. (Too bad that warning isn't documented in the owner's manual.)
UPDATE: After about a week, a couple of dozen engine starts, I turned on the A/C and then THE PROBLEM STARTED RE-OCCURRING. I started the vehicle, turned off the A/C and made sure RECIRC mode was on. I then removed the white frame/case, made sure the air filter was well-seated within it, then inserted the frame case again. It took about six cycles of this before the problem stopped reoccurring. Two weeks passed and the PROBLEM STILL DID NOT REOCCUR.
When I was cycling the reseating of the white frame/case, I noticed another two possible root causes: (1) the right-side white retaining clip on the white frame/case had become very flimsy, as though the plastic was partially broken at its elbow, and (2) the aftermarket air filter I have been using had some left-to-right 'play' when installed in the white frame/case, maybe about a quarter of an inch.
So, even though the problem was NOT reoccurring, I purchased from a Lexus dealership a new white frame/case (88899-3A080, Denso, about $20) and a new OEM air filter (87139-50100, Toyota/Lexus, about $45). When I installed the new OEM white frame/case, the two white retaining clips made much louder, more audible, clicks when seating and the frame/case feels much more firmly seated. I also noticed the front of each clip had a small black vertical mark on it that, I would guess, is where the factory has assured the clips are providing the required tension. It has been a week since I swapped in the new OEM parts … and the problem has still NOT REOCCURED.
UPDATED CONCLUSION: So, again, it appears that the seating of the white frame/case and or the air filter itself CAN be the root cause of this problem. IT DOES NOT ABSOLUTELY HAVE TO BE caused by that hard-to-access servo motor/gizmo, though it apparently can be.
(Take note the OEM air filter part number I just stated above is the filter that actually shipped with the vehicle when new. There are also some less-expensive 'YZZ' Toyota/Lexus air filter part numbers now attached to the vehicle that are actually more cheaply constructed, with fewer pleats & no activated charcoal. I would guess these air filters are designed & priced so as to better compete with the less expensive aftermarket air filters and give dealerships an opportunity for a increase in profit margin.)
Happy motoring!
Last edited by DrQuality; 12-26-22 at 06:17 AM.
09-01-23, 10:18 AM
#17
My fix was make sure the filter install with the arrow is in up position. After that start the engine and hold the temperature off button for 5 seconds or more until the massage cabin air filter reset appears. Cycle the engine power.
09-06-23, 01:39 AM
#18
Last edited by DrQuality; 09-06-23 at 08:35 AM.
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