Originally Posted by 68 TWind
If your AC is an old Armstrong unit it could be a couple of things. First, check all the mounting screws around the edge of the unit. The second area prone to leaks is where the freon and power wires go thru a hole in the top. It has to be caulked well. Finally, there is a small hole where the motor shaft for the fan on the inside goes through the top. That should be OK, but if the motor has been replaces that gasket under the plate holding the motor could be bad.
I have a lot of trouble with leaks on my old Armstrong. I'll get it fixed and then it starts again. Total frustration but it cools so well I hate to just dump it.
From 1969 and older, the factory AC was made by Armstrong. They never used a drain pan.
Rain however, could come through the AC, in 3 places.
1. The 2 AC copper lines.
2. The city power wires.
3. The blower motor gasket.
The first 2 are easily seen. The 3rd one requires the removal of the fan blower motor, so that the gasket can be replaced.
Armstrong AC's were used up to and including the 1979 models, and none of which required a drain pan.
The drain pans were first used with the 1980 models, that used the Coleman AC's.