Auto Air Conditioning & Heater Repair: AC works for a couple hours then airflow stops, honda accord ex, ac works

Question
QUESTION: Hi - I have a 1999 Honda Accord EX (4 cylinder) with the following AC problem... After driving with the AC on for an hour or two the airflow out of the vents becomes almost nothing and the air is not that cold.  If I turn off the AC but leave the fan on the airflow slowly returns.  Turning the AC back on and the air is cold but the airflow reduces to nothing quicker than the first time.  Any ideas??  Thanks in advance for your help.  -Steve

ANSWER: Steve,

I definitely haven't encountered a problem like this one before so I don't think I am going to be much help. Do you have climate control on the vehicle? That would help me give you an answer for this question.

---------- FOLLOW-UP ----------

QUESTION: Thanks for the answer.  To follow up there is no climate control, just a single knob for the entire car.  Someone I know said it might be the low pressure switch but I don't know enough about AC to figure out if this makes any sense.

Answer
It might be the evaporator core freezing up and restricting air flow through the vents and when you leave the fan on it warms it up and it thaws out and air flow returns, I would test it by running the a/c like normal and checking the pressures when this problem happens that will tell you what is going on if the evaporator is freezing up then you will have lower than normal pressure on the low side and low pressure on the high side, and normal pressures should be 96 psi at 85 degrees fahrenheit and the high side should be 250 psi.