ALT-1 How to Check and Refill Refrigerant
An air conditioning system for a vehicle is actually not very difficult to check or refill, however keep in mind that it can be dangerous if you do it incorrectly. The first thing you will need to do is to get a manifold gauge to test the pressure in the air conditioner system or A/C system. You can also purchase refill refrigerant kits at an automotive store that includes a gauge as part of the kit.
Before you attach the gauge to your A/C system identify the low pressure service valve and the high pressure service valve of the system. The low pressure valve is located on the line that connects the A/C compressor, which is usually bolted to the engine, and the evaporator, which is usually located behind the vehicle's firewall. The high pressure valve is located on the line that connects the A/C compressor to the condenser, which is usually located behind the front grille of the vehicle.
If you are still not certain which valve is the low pressure consult your owner's manual fpr your vehicle before continuing on.
Once you have identified the low pressure service valve attach the manifold gauge to it. Most manifold gauges will have clearly marked color zones that indicate if the system is "low", "filled", "over filled" or "danger". If your gauge measures anywhere in the "danger" zone you need to take your vehicle to a certified air conditioning specialist for repairs.
After checking the system and the gauge reads "low" then it is time to refill your system with refrigerant. You will need about one or two cans of refrigerant to fill your system. Take note of the type of refrigerant in your vehicle's system before purchase refrigerant at your automotive supply store.
Most American vehicles that were made after 1991 have R-134a type refrigerant while vehicles made before 1991 have R-12 type refrigerant. Do not want to mix R-12 with R-134a refrigerant. To determine the type of refrigerant you vehicle uses locate the refrigerant label in the engine bay. Since R-12 refrigerant is expensive if you have an older vehicle you may want to consider having your vehicle retrofitted to accommodate R-134a refrigerant. It is easy to do and you can find a do-it-yourself retrofit kit at any automotive parts store. Before you have the vehicle retrofitted you will need to have the R-12 refrigerant removed.
Do not try to remove the refrigerant yourself. A certified A/C technician will have the proper equipment to remove the refrigerant and will probably do it for free.
Now that the vehicle is ready attach the can of refrigerant to the manifold gauge and the manifold gauge to the low pressure value. Start the engine and set the A/C to maximum cool and the fan to the highest setting. Let the engine run for about 2 or 3 minutes. Carbon monoxide poisoning can be fatal! Do not operate the engine with the vehicle in a closed garage.
Begin filling the system by opening the manifold gauge valve or valves as required. Shake the can vigorously and watch the gauge as the system fills with refrigerant. Do not allow the gauge's needle to go into the "over filled" or "danger" zones, when refilling a system with refrigerant more is not better!
If you need to use another can or if you have finished filling the system close the manifold valves. If you need to use another can remove the empty can and replace it with a filled can and continue refilling the system until the gauge reads full. Once you have finished filling the system and the manifold valves are closed remove the manifold valve from the low pressure value. Do not remove the can of refrigerant from the manifold valve if the can still contains refrigerant.
Now that the system is filled enjoy your "cool" vehicle.
