R134a capacity?

[markj]

My coworker put an AC machine on my Accord earlier today, but the people that did the conversion from R12 to R134a under the previous owner cheated and only changed out the low side fitting to an R134a type. The high side is still the older screw-on R12 kind. So he hooked up the low side line and charged it in 0.10 oz increments until the (pressure? weight? not sure what it was) gauge on the machine for the low side read 45. He said he could probably go higher, but without knowing exactly how much R134a the system should hold, he didn't want to end up overcharging and risking the possibility of purge without the purge solenoid shutting again, thus killing my whole system.

How much R134a should replace the original R12?

[Losiracer2]

I think R134 can only achieve 85% capacity of R12 I read that on my retrofit kit I bought for my other CB7.

[Restless]

^x2. I just did the conversion about a month ago w/ the retrofit kit.

[HenRoc]

It's usually filled to the same capacity as the old system. I know Honda sells the retrofit kit for around $50 and it will come with a label that you have to put on the car stating that you retrofitted the car with R134a.

[markj]

Time for an update.

The system held up fine until today. It wasn't the coldest A/C ever, but it did the job. My coworker put the machine on it again and proceeded to charge it up in small increments once more, but after the first charge, the A/C started cycling on and off and is still doing so, rather quickly. It won't blow as cold, either. Before today's charge, the temp measured about 60 at the vents, and is now about 70 degrees.

So the system cycles on and off, on for a few seconds, off for the same, and so on. However, the system did NOT purge.

The problem is the conversion... as he explained to me, the people that did the R12 to R134a conversion only changed the low side fitting and then did whatever. I don't know much about A/C systems and I'm just starting to study them but as far as I know, I don't see a method to properly charging the system via just the low side... Anybody know how to go about doing so?