When I start my 99 Deville, Ive been getting the "Ac Low Refrigerant" message on the DID all throughout the winter. Last year I did recharge the AC with an over the counter 134a refrigerant and eveything worked perfectly all throughout the summer. Obviously there is a leak somewhere. Now that summer is here again, I expected to have to perform the same procedure to have AC for the summer....not an issue. However, when I just tested the pressure, it read a tad over 45lbs. I expected it to be much less since there is apparently a leak. Why is the pressure where it should be if there is a leak and the system is detecting a lack of refrigerant? Should I simply expell the existing pressure down to some level (25lbs?) and then refill with a new charge of 134a until the pressure is back up around 45lbs again? I am aware that the proper in shop procedure would be to recreate a vaccuum an refil, but that of course would cost $$$$ since there is an apparent leak. Easier to fix for the year for a $30 can of refrigerent which is the route I would prefer to take.