Here's what you should do instead:
1. Find a Leak: The most common reason for low refrigerant is a leak somewhere in the system. This leak needs to be found and repaired *before* adding any refrigerant. Trying to recharge a leaking system is a waste of refrigerant and money. A professional AC technician will use leak detection dye or electronic leak detectors to find the leak. Common leak points include hoses, seals, the condenser, and the evaporator.
2. Professional Diagnosis: Take your Expedition to a qualified automotive air conditioning specialist or a reputable mechanic experienced with automotive AC systems. They have the tools and expertise to:
* Pressure Test the System: This determines if there's a leak and how severe it is.
* Inspect Components: They'll check the compressor, condenser, evaporator, expansion valve, and other components for damage or malfunction.
* Identify the Cause of the Problem: Is it a leak, a faulty compressor, a clogged expansion valve, or something else?
* Repair Leaks: This will often involve replacing hoses, seals, or even larger components.
* Evacuate the System: Before adding new refrigerant, the system must be completely evacuated to remove any air and moisture. Moisture in the system can severely damage the components.
* Recharge the System with the Correct Amount and Type of Refrigerant: The type of refrigerant used in your 1999 Expedition is R-134a. They'll add the precise amount required, not just "topping it off."
Do NOT attempt to recharge the system yourself unless you have extensive experience with automotive AC systems and the proper tools. Improperly handling refrigerants can be dangerous and damage your vehicle's AC system beyond repair. The tools required, such as vacuum pumps and gauges, are specialized and expensive.
In short: The solution isn't to recharge it yourself; it's to find and fix the underlying problem causing the low refrigerant level. A professional is the best and safest way to handle this.
