Auto Air Conditioning & Heater Repair: diminished air flow after an hour of driving, hi doug, pressure switch

Question
2001 Chevy S-10 pickup, 4 cylinder, 50K miles. After driving with a cold blowing AC for an hour or so, it slowly starts decreasing the amount of cold air being blown.  Even on the highest setting (4), there is basically no air coming out, even though it "sounds" like the blower is still on.  If I turn the AC off for a while, it returns to normal.  HELP!

Answer
Hi Doug. Sounds like your evaporator coil is freezing over into a block of ice and the air can`t go thru a sheet of ice.A simple check is when this begins to happen, turn of the compressor and not the blower.Check to see if the force of air becomes stronger.If it does, your low pressure switch is not cycling the compressor off.This needs to happen to prevent evaporator freeze over.Replace the switch and see if the compressor is cycling on and off.The switch is located on the accumulatoer or also called filter.Your  last sentence explained in your question gave me the answer.