I have a 93 toyota std MT pick-up truck. The air conditioner which had
worked fine for 12 years it stopped cooling this spring. I had a can
of the old type of refrigerant and charged it and it cooled fine for
about a week. Then it stopped cooling. I had no more of the old type
freon so I put the new type connector on the low pressure side, bled
any remaining old type freon out then charged the system with the new
134a type freon, about 8 oz until it started cooling well. It worked
well for about a month but now it only cools intermittantly.

Sometimes when I first start it in the morning the air coming out is
not cool but later begins cooling. Other times it cools fine after
start-up then stops cooling after say 10 or 20 mintes. Usually I can
turn off the A/C switch for about 5-10 minutes then turn it back on and
it begins to cool again. Or if I turn off the truck and park it then
come back and start it back up it begins cooling again. When its not
cooling I can see that the compressor is spinning. Also ther is
pressure at the low pressure side.

Does anyone have any suggestions?