My air conditioner compressor fan is running but very weakly, so the house is not cooling. The coils froze over the other day and I had to let them melt off. I turned the air conditioner on again today after it had been off for 3 days and there is only a weak stream of cool air coming out of the vents.
Any ideas on what I should do?

Where are you seeing the ice?

Check your air filter or it could be a refrigerant issue. Usually an evap. Coil freezes due to a lack of air flow (dirty filter) or low on charge.

The ice was on the coils on the top of the furnace/AC unit. The blower seems to be running only slightly with very little air flow, but the air is cool.

If the coil is frozen over you won't get much air,, you need to turn off let thaw out,check for clean filter, and if it continues to freeze over again call your friendy neighborhood a/c repair man