The A/C in my car has not been blowing as cool as what I have come to expect out of our domestic cars. It's blowing about 54 F.
Looking at the sight glass I noticed that there where bubbles flowing by so I guessed that the charge may be low. When I hooked up a tank and some guages I read approx. 30psig and around 260psig. This is higher than I expected. I suppose it had been overfilled but when I added some R-12 the cloudines in the sight glass went away. A little while later the pressures on both the low and high side started fluctuating (+/-5psi) up and down in unison about once per second. I still have no condensation on the suction line.

1. If the system is overcharged why was I showing bubbles in the sight glass that went away with more charge.

2. Has my expanion valve failed or is the expansion valve adjustable?