Where is the AC low side service port on a 1986 Cadillac Deville?

The exact location of the AC low-side service port on a 1986 Cadillac Deville can vary slightly depending on the specific configuration of the vehicle's AC system and where the components were mounted by the factory. However, it's almost always located on the compressor itself.

Look for a smaller fitting, usually a Schrader valve (similar to a tire valve but smaller), on the compressor. The low-side port is usually the one with a thinner line connected to it. Sometimes it'll be identified with a color code (often blue) but not always.

To find it, you'll likely need to:

1. Locate the AC compressor: This is usually a large cylindrical component near the front of the engine, often driven by a belt.

2. Inspect the compressor closely: Look for the smaller fittings (ports) on the compressor.

3. Look for a thinner line: The lower pressure line (low side) is usually smaller in diameter than the high-pressure line.

Important safety note: Working with automotive AC systems involves refrigerants that can be harmful if mishandled. If you're not experienced in working with automotive AC systems, it's strongly recommended that you take your vehicle to a qualified mechanic for service. Improper handling can result in injury or environmental damage.