i have an '89 coupe deville and i was told that i was able to get the car's system computer readings through the temperature climate control, by holding down the warmer and off bottoms at the same time. them i was told that to go through the readings using the higher and lower fan bottoms. my question is what do each of the readings mean and where are each of the readings suppose to be at?

 

the readings are gonna display on the panel where you are pressing the buttons. to enter hold down the buttons until everything goes to 8's then let go. have a pen and paper handy cause its gonna start spitting out codes. then you can look up the codes online.