I have an older Lennox 5 ton A/C. For the last few years, I've had to replace the refrigerant about 2-3 times per year-leak in coils. It has always worked. Most recently, it was replaced, but now the A/C only cools at night. Somebody explained to me that this is because the valves on the compressor are leaking and not allowing enough refrigerant to circulate-that instead its mostly staying w/n the compressor. Does this make sense? Also, I was told that even though its an older unit, the most likely cause is that too much refrigerant was put last time and caused a leak in the valves (or the seals?). Does that make sense??