Where is the low port on a 99 buick regal for air conditioning unit?

There isn't a single "low port" in the way some systems have a clearly marked low-side service port. On a 1999 Buick Regal's A/C system, the low-side service port (for adding refrigerant) is usually located on the accumulator/receiver-dryer. This component is part of the A/C system and is often found near the firewall, but its exact location can vary slightly depending on the specific model and trim level of your 1999 Buick Regal.

To find it, you'll need to:

1. Consult your owner's manual: It might have a diagram showing the location of the A/C components.

2. Look under the hood: Carefully inspect the A/C lines and components near the firewall. The accumulator/receiver-dryer is usually a cylindrical canister with various lines connected to it. The low-side service port will be a Schrader valve (similar to a tire valve) on this component. It is usually smaller than the high-side port.

3. Use a repair manual: A repair manual specific to your 1999 Buick Regal will provide detailed diagrams and instructions.

Important Note: Working with automotive refrigerant requires specialized equipment and knowledge. Improper handling of refrigerant can be dangerous. If you're not experienced with automotive A/C repair, it's best to take your vehicle to a qualified mechanic.