Where is the low pressure service port located on a 1988 Ford E-350 with 7.4L 460CI V8?

There isn't a single "low pressure service port" in the way you might find on a modern vehicle with a specific R134a refrigerant port. The 1988 Ford E-350 with a 7.4L engine likely uses R12 refrigerant, and the system's design is significantly different. Instead of dedicated low and high-pressure ports, R12 systems often have:

* A low-side service valve: This is typically located on the dryer/accumulator, which is usually found near the front of the vehicle, often near the firewall or condenser. It's usually a smaller valve than the high-side valve.

* A high-side service valve: This valve is found on the compressor.

Finding the ports requires visual inspection. You'll need to trace the refrigerant lines from the compressor and condenser. Look for the larger, thicker lines (high-side) and the smaller lines (low-side) connecting to the components. The service valves will be located on these lines. They'll look like small, usually silver, valves with a fitting for a service hose.

Caution: Working with R12 refrigerant is hazardous due to its ozone-depleting properties. It's illegal in most places to work with R12 without the proper certifications and equipment. If your system needs service, it's best to have it professionally converted to a compatible, modern refrigerant like R134a by a qualified technician. They'll have the tools and knowledge to safely service your system and comply with environmental regulations.