Cadillac Repair: A/C and ALDL location, electronic leak detector, r 134 freon

Question
My 91 Cadillac Sedan Deville (4.9L)has been converted to the new freon but needs a recharge every spring. No one has been able to find a leak. I bought a DIY recharge kit this year after the service A/C light came on and the A/C went from "auto" to "economy". I recharged to about 40 psi and the A/C service light is still on and when I push the "auto" button it goes right back to "economy". Does something need to be reset or is there another problem?

On a separate issue, I got the procedure for setting the keyless remote but where is  the ALDL located and is the A and G terminal marked?

Answer
Converting from R-12 to R-134 freon causes numerous problems with the sensors as they are not calibrated for the R-134 freon.

You can remove all the freon from the AC system.

Evacuate all the air from the system with a vacuum pump.

Partially recharge the system and use an electronic leak detector to find the leak.

Fix the leak and then re-evacuate the system with a vacuum pump and then add the appropriate amount of freon.



The ALDL connector is located under the ashtray and the letters should be marked A and G.

If NOT, I can provide a picture of the ALDL terminal connectors and which ones to jumper if you e-mail me at: onlineautohelp@msn.com