I'll address these two together.
With the system not being very cold, it could have had a slow leak, or the compressor could have been weak.
If you have a very slow leak (as you suggest you may have in B) It is hard to find without using dye.
When you put the dye in the system, the results are not instantaneous, the car has to be driven and the AC has to be used for the dye to circulate in the system. Sometimes for weeks.
So discussing the cost to repair any leak was not an option, because no leak had been proven.
PS, it is a very small amount of dye, you would not have noticed a green vapor.
More likely what happened, your system had a slow leak and was low on freon, or the compressor was weak. The system hasn't had to deal with normal operating pressures for a long time.
Once the system had the correct amount of charge, a weak component finally failed. It happens all the time with pressurized lines, a very weak part fails, you repair that and then the next weakest part fails.
You can try it if you want, but I don't have much faith in snake oil products.
By what you have said so far, I feel that Your mechanic didn't do anything wrong and has followed standard operating procedures.
But ultimately, If you don't trust him, then go with your feelings and find a different one. You both will be better off.
Wednesday, October 3rd, 2018 AT 7:00 PM