Where is the ac low side port on a 1999 Cadillac DeVille?

The low-side AC port on a 1999 Cadillac DeVille is typically located on the dryer/accumulator. The dryer/accumulator is usually near the firewall, on the passenger side of the engine compartment. Look for a smaller port, usually with a blue cap.

However, exact location can vary slightly depending on specific engine and options. It's best to consult a repair manual specific to your 1999 Cadillac DeVille's engine (e.g., Northstar, etc.) or a diagram from a reliable online auto parts store website. Entering your VIN will help ensure you get the correct diagram.

Caution: Working with refrigerant requires specialized equipment and knowledge. Improper handling can result in injury or damage. If you're not experienced with automotive AC systems, it's strongly recommended that you have a qualified mechanic service your AC.