What is wrong with my A/C?

The problem started this Friday when our unit did not fully cool our house because there was not much air comming out of our vents. Saturday, I finally whent to check my unit and found out that the low pressure line was frozen (which probably ment that the evaporator coils were also frozen). We called the A/C tech and he took off the service panel and said that the eveporator coil was leaking. He said that he had put in 2 pounds of R-22 and the system did not hold a charge. Today, I took off the service panel to take a look for myself. I was surprised to find out that the entire bottom of the unit was literally submerged in water. I don't know how the water got there, but I'm sure that it had to leak out of the drain pan. So I checked the drain and it was clean, but the pan was really dirty. I vaced everything out with a shop vac and it started cooling our house again, except it still runs for about an hour and then shuts off for 5 minutes before restarting again. Unit: Heil PHM