From those ohm readings I am guessing a 3/4 HP. But if you purchase a 3/4 control box and it pulls more than 7 amps, your screwed. It is very rare for a cap run control box to be on anything smaller than a 1.5 HP. 1.5 HP is going to pull 11.9 amps.
There is a Schrader valve on the top of that tank somewhere. One of those plastic things comes off.
There is a Schrader valve on the top of that tank somewhere. One of those plastic things comes off.