Intermittent climate control panel problem, 97 LS400

LSbr · November 16, 2021

I have read through the climate control diagnostic and repair threads such as this one on codes. However, I have an issue that I haven't yet seen described.

Intermittently, some buttons on the climate control panel stop working - the rear DF won't turn on, the driver's side temp control will turn the temp up but NOT down, and front defrost only works in auto mode. Then after a while, I will start the car up and it works again. One time when it was not working, I shut the engine off, restarted, and it worked again.

When I ran the diagnostics, I got two codes but got a beep with both so I think it means it's not a current problem:

21 (the solar sensor one that I understand is normal to get when it's dark)
24 (and for this one, I have not yet seen any description for it... the guides skip that number.

When I ran the fan and door actuator diagnostic, all seemed well. Also I just replaced the cabin air filter just in case.

I understand that the climate control control panel shares the same power source/fuse as the front cig lighter, and one time the control started working again when I removed a bluetooth/charger plug that was in the lighter. But probably that was a coincidence, and the problem still happens with nothing plugged in.

Any advice? Is this worth replacing the control panel, or should more diagnosis be done first?

Thanks,

-Tom

Edited November 16, 2021 by LSbr

LSbr · November 17, 2021

New information:

1. I have found that the problem goes away after 1-2 minutes of starting the engine. Then everything works fine while I am driving. But when I shut the engine off and then later start it again, the problem comes back... then goes away again.

2. Something that might have caused it - a couple of weeks ago, I removed the center console cover to fix the front and rear cigarette lighter/12-volt charging port. Maybe I tugged on a part of the wiring harness that goes to the climate control panel? Maybe it's a coincidence?

Thanks for any input and advice!