Perhaps the OP can clarify the sequence of events. It sounded to me like he charged/topped off the systems and then started having trouble. What he describes is classic overcharging symptoms - right down to the fact that it runs longer when cold out- but without gauges he can't know this for sure. I suppose he could try reducing the amount of refrigerant in the system and see if that cures it.

I agree with Larry than R12 is the best way to go with the systems that were designed for it. I have never been happy with any converted system, period.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz