What is the freon capacity of a 1988 Chevrolet r3500 crew cab pick up?

There's no single freon capacity for a 1988 Chevrolet R3500 crew cab pickup. The amount of refrigerant (R12, in that era) needed depends entirely on the specific air conditioning system installed in that particular truck. The size of the compressor, the length of the lines, and other factors all play a role.

To find the correct amount, you need to:

1. Locate the AC system's sticker. This sticker might be on the compressor, under the hood, or even inside the glove compartment. It will often list the refrigerant type and the charge amount.

2. Consult a repair manual specific to your truck's year and model. A Haynes or Chilton manual would be a good source.

3. Take it to a qualified AC technician. They have the tools and knowledge to properly diagnose and charge your system, and this is the safest and most reliable method. They can also identify any leaks that may exist.

Trying to guess the amount is risky and could damage your AC system. Never attempt to add refrigerant without proper equipment and knowledge.