: No A/C, digital readout won't stay on AUTO.

07-20-11, 05:04 AM
This is for an '89 Deville. Recently the air conditioner seems to have stopped working. There should still be freon in it. When the button for AUTO is pushed it changes to AUTO for something like half a second and then flips right back over to ECON. Any ideas a semi-amatuer? Thank you.

07-20-11, 10:49 AM
What things should be and what they are often cause many a headache. It sounds like you had the A/C switched on before turning the key to start the car, all while you had an insufficient charge in the system. Read insufficient as not full.

If the A/C unit read a low system pressure and moved to kick out the compressor, that's the SECOND symptom you should get. The first is your Check Air Conditioning light. If it stays on for more than five seconds when starting the car, it's a probability. It's a feature to save your compressor when you don't have a sufficient charge. Check your diagnostic codes to verify it.

Clearing the codes will get the A/C compressor functioning again, but that's not to say it won't happen again if the charge is low.


07-20-11, 11:11 AM
If your mechanic is not used to working with Cadillacs, you may well need to learn how to clear the trouble codes, then teach your mechanic how to read and clear them. I know I did and he's one of the most highly regarded wrenches in the area. He just doesn't see a lot of Caddies.

If you have a low charge when cranking the engine and the A/C is ON, the computer will see it as NO charge.

The System will kick out for all sorts of reasons. Too high a charge is one of them. Malfunctioning high and low pressure switches, clutch relay.... There are many reasons. The charge is only one of them, albeit one of the most common. The end result is that AUTO ceases to be an option with your climate control.

Read, record and clear the ODBI diagnostic codes. You'll see the sticky at the top of this section. Follow the directions there. With my '93, you read the codes where the fuel gauge is, not on the climate control. Had me scratching my head before I realised I had to work on one side of the column and read on the other. A code of .7.0 means ready for instructions. F47 is a low refrigerant warning.