Front A/C problems, is this piece broken?

[mikeyd]

My daughter drives my '00 LC100 with 250k+ miles. She told me the front A/C wasn't working anymore. I investigated and here's what I found:

• Rear A/C works as it should.
• A/C fuses are all OK.
• Car parts store A/C recharge gauge showed pressure was OK.
• A/C diagnostic check showed a code for: Air Mix Damper Position Sensor Circuit.

Looking under the passenger footwell at the servo motor and gears, I noticed the metal gear was traveling past the plastic guide.

What I don't know is if this is normal, as I could not locate any pics on the internet or IH8MUD showing the plastic track and metal servo arm.

I was able to nudge the metal arm back towards the centerline of the LC100 and my front A/C returned.

► Is the white plastic guide broken? Should the metal pin be able to travel past and out of the plastic guide?

► What does the trouble code tell me?

 

[mikeyd]

If this plastic track/guide is not broken, what might be causing the servo motor to stick on full heat (dash knob to max heat)?

To re-state, the servo motor will go from cold A/C to full heat when turning the dash temp control knob to max heat.

Twisting the dash temp control knob back to max A/C does nothing. The servo motor will not move the gears/arm without a nudge on the metal pin, which causes the motor to turn and cold A/C is restored.

What might be causing the servo motor to hang up on full heat?

MikeyD

 

[Malleus]

I was born and raised in middle Tennessee, and I had to look up Smashville. I must have been away too long.

The code tells you the position sensor doesn't "see" the blend door in the correct position when you've selected cold. Nothing you didn't already know.

The 2000 LC FSM (in the Resources section, or just use the link) has a complete description of the system, and how it works, including illustrations of what the components look like. It would be easier for you to look it up, than for me to describe it to you.

 

[Malleus]

EDIT: OK, I checked, the FSM illustration sucks (Pg AC-31; real page 2091 of 2157 & pg AC-74; real page number 2134 of 2157). Download it anyway.

Let me go out and look. BRB

 

[Malleus]

Well, I guessed wrong. Again. My current project 100 is a 2000 LX470 and the Lexus has the AHC ECM mounted where the 2000 LC air mix motor is mounted. So, I couldn't find the actuator linkage; it's behind the center dash and I'm not tearing that out to satisfy my curiosity. Sorry.

However, form what I could see, both ends of the control linkage arm (rod) are connected via plastic bits at both ends. Yours looks like it's missing one.

 

[Malleus]

Maybe @2001LC has a photo of what's behind door number three...

 

[mikeyd]

Thanks Malleus. My guess is the plastic guide rail is not broken at the end. But, the air mix motor is definitely not working as it should.

It reads like the problem is with the air mix sensor. Where is that...anyone know?

 

[Malleus]

It's in the center console area, on the passenger's side, according to the FSM, attached to the motor:

 

[Biga27110]

Does anyone know if this replacement of the servo is possible without pulling out the Dash?