I have a 2004 Honda Accord with AC that blows hot air. When failure started in the winter, the drivers side would blow hotter than the passenger side. Now they blow the same temperature: hotter than hell.
It seemed other people had similar issues online, and a recharge fixed it. I also talked to a technician at my local Honda dealer, and he said it sounds like a low refrigerant issue.
So I went out and bought a can of AC Pro (My car takes 19oz of R134A) and tried charging. When the compressor was off, it read high pressure. When the compressor turned on it dropped to 0psi, and stayed there. I used most of the can with no change in air temp.
EDIT: While recharging, the gauge came unscrewed from the nozzle, but stayed attached to the fill point. Not sure if this would cause the pressure to drop to 0psi, as it has a trigger to keep refrigerant from escaping/allow it to enter