Why you shouldn't do it yourself (unless you're experienced):
* Finding the Leak: Low refrigerant is a *symptom*, not the problem. You *must* find and fix the leak before adding refrigerant. Otherwise, you'll just be wasting refrigerant and money. Locating leaks requires specialized equipment like leak detectors.
* System Pressure: Adding refrigerant requires understanding the system's pressure. Too much or too little can damage the compressor or other components. You need gauges to measure this accurately.
* Refrigerant Type: Using the wrong type of refrigerant can severely damage the system. You need to know the specific refrigerant required for your 1999 Ford Expedition (it's likely R-134a, but check your owner's manual).
* Safety: Refrigerant is under high pressure and can cause serious injury if handled incorrectly.
What you should do:
1. Take it to a qualified mechanic: This is the safest and most reliable option. A professional mechanic has the tools, knowledge, and experience to diagnose the problem, repair any leaks, and recharge the system correctly.
2. Diagnose the problem: Before adding any refrigerant, a mechanic will likely perform a thorough inspection, which includes:
* Leak detection: Using specialized equipment to locate the leak(s).
* Pressure test: Checking the system's pressure to ensure it's within the correct range.
* Component inspection: Examining the compressor, condenser, evaporator, and other components for damage.
3. Repair any leaks: Once the leak is found, it must be repaired before adding refrigerant.
4. Evacuate and recharge the system: After repairs are complete, the system will be evacuated (removing air and moisture) and then recharged with the correct amount of refrigerant. This requires specialized equipment.
In short: While you *can* buy refrigerant and a recharge kit, doing so without the proper knowledge and tools is highly discouraged. The potential for damage to your vehicle's AC system and potential injury far outweighs any perceived savings. Have a professional handle this task.
