Christmas Tree lights from A/C Control Panel, '93 Lesabre

[brucied]

My A/C/heating control panel lights on my '93 Lesabre operate spontaneously and intermittently. Most characteristic problem is a Christmas Tree effect, in which the 8 panel buttons plus the rear defrost button blink sequentially, about a second each, in a continuous circular pattern, one after the other. The vents and A/C respond, just as if the buttons were pressed. Restarting the car tends to solve the problem, temporarily.

I assume it's a computer problem of some sort, but I don't know where to begin.

Thanks in advance

[imidazol97]

Originally Posted by brucied

My A/C/heating control panel lights on my '93 Lesabre operate spontaneously and intermittently. Most characteristic problem is a Christmas Tree effect, in which the 8 panel buttons plus the rear defrost button blink sequentially, about a second each, in a continuous circular pattern, one after the other. The vents and A/C respond, just as if the buttons were pressed. Restarting the car tends to solve the problem, temporarily.

I assume it's a computer problem of some sort, but I don't know where to begin.

Thanks in advance

My first guess would be power to the dash unit. Or the unit might be bad. The battery connection should be good and clean. If it's a double cable at the battery be sure to check in between the positive contacts. Turn off the AC power with the key ON before removing battery cables. Then remove cables with key off.

You might have a contact problem at the ground buss under the front plastic sill of the driver's door. Do anythiing else not work or work sporadically.

Try hitting that area and see if the vibration will improve the contact temporarily. If you're in a climate with lots of water dripped off shoes as your feet go in keeping the carpet wet by the door that's a higher likelihood for checking at least.

[Hquest]

I had a similar problem with my 93 LeSabre. After redoing all the grounds without helping the problem I disassembled the A/C control box and found the IC Chip had cold solder joints, re-flowing solder on each of the pins (can't remember how many, maybe 16) and the problem is gone. That was about a year ago, and I drive her daily.