Larry and Dave,
Thanks for the response.
The conversion was done by evacuating the R12 and adding R134 and oil. No other parts were replaced. There doesn't seem to be any major leaks as I have added only one 12oz. can since. The system has adaquate pressure when it finally decides to start working - after 10 minutes of driving or running in the driveway. And it cools as well as can be expected, dropping 100+ outside temps to around 45-50.
The conversion was done last summer and has been through it's paces here in Albuquerque for over a year.
When I begin driving with A/C on and fan switch on high, the fan will begin to blow low after 10 minutes and over the next few minutes will step up to high. I then switch to medium when comfortable. As I recall the cooling used to begin in a matter of seconds, not tens of minutes.
How do I trouble-shoot the climate control?
Dave, can I get the details of your conversion project?

Jacob

This is an immaculate car with 120k miles and a recent conversion to a 4-speed manual transmission. I really like it!!