Newbie here. Ok, back in January our compressor froze up for about 3 days during the coldest days we have seen here in SC. We noticed that our power bill went from $240 to $550. I knew something was wrong but wasn't sure what it was. Had no idea it would could be the HVAC system from the heat strip running all the time. Anyways, I had a Hvac tech check it out yesterday and he said the compressor was bad and the system was about 4 pounds low on freon. (R22). The breaker was tripped and when he flipped the breaker back on and the unit tried to kick on, the breaker tripped again. With the system being that low is this what caused the compressor to stop or is there some type of cut off for the compressor if a detection of low freon. Also the unit was manufactured in 1997, so I'm thinking of a new complete system. Can someone give me some options as if it's better to replace the heat pump or the complete system and if the new 410A would be a better choice since i was told that if I have another R22 unit installed I would not be able to get the freon after 2014. One last thing, the house has about 1950 sqft of heating/cooling area, it's currently a 2.5 ton and was told we needed close to a 3.0 ton. Does this make a big difference in heating and cooling. Thanks for all the help.