I have a 91 deville and i have no haet or nothing. I have checked all of the fuses and there good. When i put it on auto the service ac light comes on. i have nothing. Where should i start.

 

here are many places to start but you can hold the off and warm buttons for a few seconds if you have a digital dash and look at the fuel display for any f codes like F_ _ .

 

Go into the On Board Diagnotics by pressing the Off and Warmer buttons on the climate control at the same time to access the trouble codes (hold the buttons for about 4 seconds until the entire display lights up, this will work whether you have an analog or digital dash - the engine should be off when you do this). Write down all the trouble codes that appear (depending on the car - they will appear in the Climate Control or the Information Center). The following website will identify what the codes are: http://members.accessus.net/~090/dtcobd1.html

Write back with any questions.