A/C leak

If your 1999 Honda Accord's AC system won't hold a charge despite not finding any visible leaks in the engine compartment or the evaporator case in the glove box, there are a few potential reasons for the issue:

Small Leak: AC systems can develop tiny leaks that may not be immediately visible to the naked eye. These leaks can be challenging to locate without specialized equipment. Even a small leak can cause the refrigerant to escape over time, leading to a loss of cooling performance.

Leak in Hidden Areas: The AC system has various components and connections that may be located in hard-to-reach areas, making it difficult to identify leaks visually. Leaks can occur in areas like the condenser, compressor, hoses, or fittings, which may be hidden from immediate view.

Seal or O-ring Leak: AC systems rely on seals and O-rings to maintain a proper seal between components. Over time, these seals can deteriorate and develop leaks, leading to refrigerant loss.

Evaporator Leak: Even though you've checked the evaporator case in the glove box, the evaporator coil itself, which is inside the dashboard, can develop leaks, and it may not be directly visible without disassembling the dashboard.

System Overheating: If the AC system is running at high pressures, it can lead to refrigerant escaping through relief valves, causing a loss of charge. This can be due to overcharging or issues with the compressor.

Using stop leak products is not recommended as a long-term solution, as they can potentially cause further issues with the AC system and may not address the root cause of the leak.

Please go over this guide.

https://www.2carpros.com/articles/air-conditioner-leak-detection

Please go over these guides and get back to us.

Sometimes it wont if the leak is small, it usually is the front compressor seal.