I hope someone can help me with an A/C issue. The air conditioner blows very hot heated air, not outside ambient warm air on all settings. The A/C light is green, the compressor engages and the lines under the hood are cold. The fan works on all settings. When the key is turned on there is a sound in the dash for 10 seconds that sounds like a pump or motor running, it is a new sound that is pretty loud. I suspect that inside the plenum a door is stuck but I have no idea where to look or how to find it. Any help would be appreciated.