A/C, heater temperature knob, ventilation switches, rear defroster switch does not work

TWITSEND

MEMBER
2000 HONDA ACCORD
4 CYL
2WD
AUTOMATIC
168,000 MILES

The fan works, but none of the ventilation switches light up, the recirculate, A/C and rear defroster switches do not work nor light up either.
If I remove the entire climate control panel and disconnect the wire harnesses and then reconnect them again it fixes the problem, for a day.
But the next day when I start the car up it is back to not working.
I have been able to restart the car several times in the first day after reconnecting and everything works fine.
But about twelve hours later it is back to not working.

Also, the ventilation control buttons do not light up nor work.
I cannot control which area air comes out from system.
The climate control panel dash lights work, but the individual switch lights on each button selected will not light up.
I mean at night the back lit dash lights work so you can see each switch but whichever switch you depress it does not light up the indicated switch.
You cannot turn on recirculate button, rear defroster button, A/C nor activate where you want to direct ventilation switches, IE; floor, vents, or front defrost buttons.

2 Replies

STEVE W.

MECHANIC
13,463 POSTS

From your description it sounds like the control head itself has an internal failure. The fuses that power it power multiple items as well as it and it seems to be the only item that does not work. Your unplugging and re-plugging that get it to work for a time also leans toward internal failure as that disconnects both the switched and constant power to the controller and is forcing it to "reboot". It works until the component inside fails and stops. My guess is either a failed/failing capacitor or some cracked solder joints on the control board. This could likely be confirmed with a factory level scan tool that can "talk" to the various systems including the control head and verify that it is shutting down. Or hit a salvage yard and find a different control head, probably much cheaper than having it tested.