Window Air Conditioning working or not?

[Ranger001]

Hi I bought a Frigidaire Window Air Conditioner (FAL124K1A1) in 2001 @ $400.00. At first it worked fine but then, last week it demised. It was under warranty and was repaired. However since it came back it seems not to cool effectivly & quickly like it use to. the tech says its ok but I think different. My question what formula can I use to see if the unit is working properly? What tools can/do I need/use? I wrote to Frigidaire and they replied: ".....This is a 12,000 btu unit; it should have a 20 - 25 temperature rise across the coil. Difference between the incoming and out blowing air." What does this mean? What does "across the coil" mean? Please advise, Thanks!

[SQLit]

you answered the question "it should have a 20 - 25 temperature rise across the coil. Difference between the incoming and out blowing air."

[Don]

turn the unit on and use a quality thermometer and measure the temp of the air at the inlet /return to the unit and then at the discharge/supply outlet to the room. subtract supply from return temp and.. taaaaddddaaaa Don

[Stormin Mormon]

Well, if the air blowing out of the AC (into the room) is rising 25 degrees, then you very obviously have installed the unit upside down. turn it right side up, and it will start cooling.

Hint: I've found that a fan blowing TOWARDS the AC cools the room better than a fan blowing away from the AC.

"Across the coil" means air coming into the unit, and air blowing out. If the tech support guys say rise, then they mean the outdoor air. Measure temperature of the air sucking in the side of the AC, and the temperature of the hot air dumping out the back. Is the hot air noticably hotter than the air coming in the side?