Where is the low pressure valve located?

Hi,

Because of the model year, I don't have specific pics. However, I can still help.

If you look at the AC compressor, there will be two lines. One will be larger in diameter. The larger one is the low pressure. It will go from the compressor to the firewall (see pic below). Follow it until you locate the port.

Also, here is a link that explains how to locate it and explains how to add freon. Take a look at it and there is also a video that is helpful.

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

One other issue. In 1988, the refrigerant used was called R12. That is no longer available. In most cases, by now the systems were retrofitted for R134A. Make sure you use the correct refrigerant. If it was retrofitted, the connector for the R12 should not fit the R134A adapter that would have been added. The adapter should be mounted to the fill port valve or Schrader valve.

Let me know if this helps.

Joe

See pic below.