Is there a low side service port.

The lower side service port is located on the large tube headed from the firewall to the rear of the compressor. Here is a diagram and some guides to help you get the job done. Low side port is featured by a red arrow. (below)

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon

and

https://www.2carpros.com/articles/how-a-car-air-conditioner-works

and

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

and

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Please let us know what happens so it will help others.

Cheers, Ken