AC Diagnostic Help Please

[Adam R]

Last week the AC in our 99 LC started acting up. It occasionally only blows hot air and at other times it works fine.

We took it the dealership to have the AC recharged and it turned out the AC was nearly fully charged. As the technician started to wrap things up, the LC started blowing hot air for him as well. He and I traced the likely problem to the Front Air Mix Damper Control or what I like to call the “Servo Flapper Door” that is located in the passenger side footwell. Sometime this door works and sometime it does not.

I ran the diagnostic procedure for the AC panel I found in the archives and this is what it came back with.

After doing the 1 second interval blinking of all panel lights, it returns the following flashing light pattern.

First the Rear Defrost and Air Flow to Upper Body lights blink.

Next the Air Flow to Upper Body and Rear Fan lights blink.

Then the Rear Fan and Position #2 of the air flow (the one higher than the Low setting) lights blink.

After the series of these 3 blinking light sequences, it repeats again.

Can someone look up the codes in the FSM, I believe DI-624, and tell me what these light codes possibly indicate.


Thank you,

Adam

 

[LandCruiserPhil]

Good luck and post up your findings

 

[LandCruiserPhil]

This could be helpful also

 

[cruiser100]

If it blows warm also check the fan clutch, could be going south on ya...

 

[Adam R]

Thanks for the schematics!

I don't think it's the fan clutch since that is working as it should and I replaced it last year.

However, here is where I stand now.

I pulled the LC outside (it's a sunny day BTW) to try and trouble shoot using the voltmeter.

Upon startup of the LC, I could hear and see the servo motor working.

Two minutes later, it was no longer working as you moved the temp switch from cold to hot.

Fast forward 10 minutes, it's working again. Over the course of the next hour, the servo motor worked as it should and I was able to trace the function of the 5 wires that go to the servo control motor.

I re-ran the diagnostic codes and get the following errors

RrDEF/FACE
FACE/Rear Fan (no apparent trouble code for this combo)
RrDEF/M1
Rear Fan/M1 (again, no apparent trouble code for the Rear Fan switch blinking.

Since Rear Fan is not even listed as a trouble light indicator, I'm not sure what to do about this one.

For the time being, I'm going to wait until it doesn't work again to see if the servo motor is being sent the voltages I recorded when it did work. That will hopefully point to or rule out the servo motor. The next item would be the AC amplifier based on the FSM recommendations or possibly change out the entire servo control motor assembly.

Does this sound reasonable?

Thanks again,

Adam

 

[CappyKD]

Did you ever fix this?

 

[Zooguy]

Did anybody figure out what rear fan means in conjunction with other LEDs. Trying to figure out my AC and none of the pages I'm finding have a "Rear Fan + xxx". Indicated for any trouble codes