my 92 does that with the original r12.. cool, never cold, has taken 'forever' ie 10 miles to cool since i bought it new.. cools faster if i put the fan setting in the middle not full blown..open up all the doors and then turn it on to get the heat out..leaving the windows cracked alittle does nothing to advance the heat out of the car.. i have a dark car and those windows are like a green house.. the molecule for r134 is larger and it works differently from the r12 doesnt cool as well.. if its truly overcharged it wont cool very well.. the compressor will go on and off constantly..