Hi Everyone!

Friday the temp here went over 90 degrees and I had to run the A/C constantly just to stay on the warm side of comfortable. The A/C used to be so cold that I would have to turn it down, so I got to wondering if I had developed another leak in the A/C.

Car History:
The car has had A/C leaks before. I had a garage convert it to R134a and fill it with dye. That leaked out in 2 days but they found the source of the leak (can't recall now - think it was a fitting or something). Then it leaked out again 2 weeks later - this time a rotten O ring on the evaporator coil under the dash. Since then, the A/C has held for 2 years.

Today:
Since I've been getting frustrated with other issues on the car and am getting close to wanting to replace it, I didn't want to take it to the garage again. So I bought a $20 A/C gauge to measure the low side system pressure.

Based upon the outside temp of 77 degrees this morning, the chart that came with the gauge said the system should register between 35-45 psi when the ambient temp is at 75 degrees. When I measured it, it was around 32-33 psi. In retrospect this was probably a dumb decision, but I went to Autozone and bought a 12 oz can of R134a with the Dye pre-mixed in with the refrigerant. My goal was to get the pressure up to about 40 psi.

With the car running on Max A/C, I followed the instructions on the packaging by first connecting the canister to the gauge but the valve in the off position, connected the gauge to the low side connector port on the A/C line, then adjusted the valve to puncture the top of the canister, and then began to open the valve to allow the refrigerant to flow into the system.

According to the instructions, you're supposed to agitate the canister while the refrigerant is flowing into the system. But what I found odd was then when I agitated the can, the pressure on the gauge spiked into the 40s, but immediately dropped back down to the upper 20s / low 30s as soon as I stopped agitating the canister and remained at that pressure by the time I finished emptying can into the system. (Don't know if this matters but while emptying into the system, the canister became cold and condensation formed on it.)

The Problem:
The pressure on the low side port now reads at 28 psi instead of 33 psi like it did this morning.

My Question:
Since I had pressure continually through the process of emptying the refrigerant into the system - even when the can emptied out - I presume that my connector was in fact properly connected to the A/C line. So is it safe to conclude that I do in fact have a leak in my A/C system that just doesn't hold pressure about 33-35 psi?

Any thoughts on whether this indicates a leak or if I did something wrong this morning?

Thanks in advance,
Jonathan