Installed a 2 ton air conditioner to my furnace but I have one question. The low and high side pressures are reading high, the high-side is around 450 psi and the low-side around 250 psi. wondering if the system could be over-charged. It has enough R22 for 20 ft of line-set I used 23 ft of lin-set. There is also a hiss coming from the inlet of the evaporator, has a fixed orifice.