I have a 1989 Deville.

Recently, my Fuel Data and Electronic Climate Control displays suddenly started displaying just the letter "c". Worse, it is blowing warm air out of both the front defroster and floor heater. Not fun when it's 92 degrees outside.

I've tried entering diagnostic mode but it will not enter...I just keep getting a c.

Do I need a new ECC computer? Any ideas on what I can try.

Thanks!!