Anyone experienced air mix servo motor deterioration?

My driver side vent is blowing warm air on hot days when pass side is blowing ice cold. According to the threads in this forum (for RXs and GSs) it is very likely the air mix servo motor malfunctioning.

I found the servo under the dash just above the throttle. Easy to remove saw only two screws holding it. Instead of remove and clean like other adventurous owners here I prefer to just replace it and keep the old one for clean and repair at my own leisure.

Part No I found for es 350 is 87106-33270. This is for the driver side. $200 at the lexus of alexandria.

I also found the same Part No for Toyota $118 (lexuspartsnow.com) -$150 (Kay Jennings Springfield Toyota)

What do you guys think of its likely hood that its the same part. Any Cautious folks out there?

 

check out the sewell site for the part # and cost.

http://lexus.sewellparts.com/oem-cat...S350-2009.html

the cost as a CL member for that part # is $115

 

I do get the discount. The site says $161

 

its $161 when i dont log in and $115 when I do log on
87106L 8710633270
SERVO SUB-ASSEMBLY, DAMPER 01 Ships 24-48 hrs $189.08 $161.97 $115.34

 

Before I purchase a servo motor I decided to try the least costly thing first. Remove the driver side servo motor take some pictures and while I have the servo out clean the internal contact fingers and the gear contacts. They looked so clean I am a bit disappointed after doing it. I am going to take it out on a test spin in a minute, and will let y'all know if this fixed it. If not I'll take it to a tech to check on the refrigerant pressures. uploading picture on this site is not straight forward. I get a popup asking for a URL.

 

So its not the servo. Servo was working fine. But blowing lukewarm air through driver vents. Only the center passenger vent is blowing ice cold. Maybe its low on refrigerants

 

there is an on screen display w or w/o nav that u can access that will give u dtc codes that may point u to the correct ac problem area. ive att the 2 svc manual files that initiate the display. I can give u access to much more info if u want to proceed down that route.

fyi DTC B1446/46 is the Air Mix Damper Control Servo Motor Circuit (Driver Side)

 

Thanks I'll try this in the morning. Let you know how it goes. Looks like I'll need a degree in engineering, but I'll see if I can muddle through.

BTW my dealership wants $390 just in labor parts are extra. This is a minimum I'll escape with if I take it in.

I appreciate your support. BTW I was in Ontario last week. Was visiting my daughter in Rochester decided to go see the falls for a day trip.

 

No new discovery update.


Tried the indicator checks and and sensor checks. DTC code flashed 21 and 24 respectively in one second intervals. Info in the PDF doc said that would be normal when checked in dark place. Which I was, in my garage.

Did the sensor mode checks and the system cycled through all settings then I entered indicator checks again, the same codes 21 and 24 flashed.

Prior to doing this I wanted to confirm to my self that its not the servo motor malfunctioning which was leaving the hot air damper slightly open in the full cooling mode. Here is what I did. Removed the servo motor then I noted the position of the hot air damper gear arm in the fully closed position. Then I reinstalled the servo motor. Then I started the engine with the ac in full cooling. Re observed the damper gear position made sure it was still fully closed, and it was, then checked the air temp coming out of the driver vent. Still noticeably not as cold as the passenger vents.

Here are my assumptions.

One compressor (so if refrigerant is low the passenger side should be effected as well).

One evaporator (incl expansion valve) (passenger side should be effected if this was bad )

Temperature on either side is controlled by how much air is passed through the heater cores with split ducting mix with cold air for left and right (still one heater core in the cabin).

Only one fan speed for both side which means temp is controlled via regulating how much hot air is added to the cold air ducting separately for either side.


So I have a theory for this witch hunt.

The cold air favors the passenger side simply because the passenger side ducting is upstream of the driver side. When the AC system is hitting all cylinders the passenger side will always blow colder air than the driver side (when not regulated but not perceived because the passenger side servo would add hot air to normalize/regulate to maintain temperature).

However when the cooling efficiency is not 100%(or when the refrigerant is low) both dampers passenger side and the driver side damper would be closed struggling to get to the desired low temp with passenger side air vents blowing colder air than the driver side (no luxury of adding warm air to the mix because the air is simply not cold enough)

The best case ending for this novel is the system has lost efficiency because the refrigerant is low and that is all I need. Worst case may be bad expansion valve, bad evaporator, or bad compressor, or bad magnetic clutch.

Bottom line is I think I have to take it in with a blank check. I'll take it in after I check some system pressures.

 

I am not sure if this would be the right place to post this don;'t want to highjack your thread
im not really familiar with how the hvac system works
but would i be having an issue
if when i have the mode set to floor and the speed all the way up i notice that its blowing out the left and right side dash vents not the center but the right and left side vents ?
would this be a mix door or a mode door issue ?

 

dtc code 21 and 24 refer to a faulty Solar Sensor Circuit (Passenger Side) and driver side resp. I would perform the test in the lighted area to see if u can eliminate those from contention. ie code 24 may still show up as a fault in the light. and "...When there are no problems, DTC 00 is output...."

many of the things u mention in your witch hunt would have a dtc code showng

as well here is more info on vent positions and a troubleshooting table

 

Thanks nevernu for adding more weapons in my witch hunt arsenal. You are right about the dtc codes.

Seems to me like the photo diode voltage provide data for the blower speed and the inlet servo.

BTW I ran across a diagram in a internet search some TOYOTA ACs have a sight glass in the pressure sensor block. I may have to look for it. My old CIVIC CVCC used to have a sight glass I used to use as a indicator when the refrigerant volume was low. It would show bubbles in the sight glass during compression cycle when I needed to recharge.

I'll post update maybe tomorrow night if I get the motivation after work.

 

ThumperPup

My Acuras does the same thing. Did when I drove it out of the dealership new. Always blew out of the side vents when I have the setting to the floor. ithink it does the same thing on my ES as well I have to check. I rarely have blower going to the floor on my ES.

I dont think there is anything wrong.

 

ok cool thanks
the only reason i ever have the blower going to the floor is because i am a culinary student and i bake alot in school also
so with it being in the 90s outside and if i have a butter cream cake or truffles that i just made and i don't want them to melt i put them on the floor with the temp set to low and blower on high with mode set to floor sometimes it does help it helped me drive 260 miles to tampa a few weekends ago with a buttercream cake LOL

 

With help from ELITech I decided to embark on topping off my A/C freon to fix the warm air out of my driver side vent. ELITech suggested that our cars driver side vent can blow warmer air than the passenger side when the freon is low.

I got a 15" 134a fill hose extension from eBay and $15 can of 134a from Advance Auto today and I filled from the low pressure side until the low pressure side reached 35psi while watching the sight glass for the bubbles to disappear.

When the low pressure side reached 35Psi all bubbles disappeard from the sight glass. I checked the air temp on the driver side and its COLD!!!

Thanks ELITech and NeverNU for responding to my questions.

For now I saved $260 by DIY