I have a 2008 Dodge Caliber. The AC was not blowing very hard and the air was not cold. I changed both air filters (one under the hood and one in the cabin) and this solved the air flow issue. The air is still not cold, however. Should I take it to a mechanic or give one of those refrigerant cans a try? Many thanks for the help!
If you are not familiar with working on AC systems it would be best to take it to a mechanic. Those cans of refrigerant with a cheap low-side gauge are crap, you can't tell what's going on with that, you need a full AC manifold gauge set. Also many of those cans contain sealer which can further damage your AC system as well as expensive equipment at a shop when you wind up taking it there. Also there are other problems that can cause lack of cold air such as the blend door not operating properly. (Your AC system could be running full blast but you'll never know it if the blend door is letting hot air in from the heater core through.)
If you are determined to work on it yourself buy a gauge set (an inexpensive set for about $50 is fine for home use) and a some pure R134a with no sealer. (A 12 oz can of pure R134a currently sells at WalMart or Tractor Supply for under $5/can.) There are youtube videos you can view to familiarize yourself with diagnosis by system pressure and the procedure to charge a little bit in at a time and check the results. Make sure to wear safety goggles when handling refrigerant. Take your time and don't get ahead of yourself.
This is not rocket science but is requires different knowledge and tools than typical shadetree maintenance and repair operations and it's very easy to do the wrong thing and make matters worse.
Can you please explain how the sealer in a can of refrigerant can damage an AC system?
Sealer can clog up various parts of the AC system. It solidifies in places where it's not supposed to, ruining expansion valves, orifice tubes, driers, even compressors. (A friend of mine found this out the hard way and had to replace his entire AC system after using sealer-laden refrigerant.) If after using sealer you take your car to a shop to have the AC worked on the sealer can damage their equipment, which you would be responsible for. (Typically they will refuse to work on an AC system that is known to have sealer in it. There are test kits for that.)
Scotty answers your question at 4:02 below
