Air Conditioner Conversion Kit

I don't mean this negatively, but how do you think that will help? Accumulators are used to capture and hold liquid refrigerant, sending the gas to the compressor, because compressors can grenade if they're fed liquid. There are r134a systems that use accumulators, especially on dual evaporator systems. but nearly all use a receiver drier in the liquid line prior to the metering device so that the metering device is fed liquid refrigerant. I don't think adding an accumulator will improve your performance.

I don't know what you've all done, and I haven't gotten through your entire build thread yet.  But you've done a lot of good things here with upgrades and all, I can only imagine how upsetting it is to have poor performance, when it should be freezing you out.

It's simple for me to suggest it as I have a machine, but my first step for diagnosis would be to weigh out your charge and see if it's low. Did you add any uv dye to this when you originally charged it? The dye makes leak finding more of a visual inspection.

2nd would be to look at why the circuit breaker is blowing. I'd check draw with an amp clamp, and then maybe do voltage drop across different points in the circuit. Maybe check that your evaporator isn't plugged up and that your cowl isn't obstructed. It's interesting you mention the fan not blowing hard, as any air restriction would cause higher amperage draw from the fan. Running a relay for high speed isn't bad, and a lot of systems do that to avoid running high amperage through the switch. I don't know factory things enough to suggest something, but looking at my factory manual I don't think a DIY install would be difficult.

Another tip for better AC would be to install a shut off valve of some sort on the heater hoses, as hot coolant in the hvac box isn't helpful when you want max ac performance. Easiest would be a manual ball valve in one of the hoses, or various vehicles had cable type and vacuum type valves that one could install. Make sure your recirc door is functional as well, guys will typically tee off the recirc door vacuum line to run a heater hose shut off valve.

FYI if you're running a sanden 508 it would have 80% capacity compared to the factory york. That's if you're running the same diameter pulleys. Might or might not be your issue. The sd709 you mention would be approx 90% of the york. I'm a fan of the sd7 enhanced line, as that would have you at 13 in.³, more then the factory york's 10.3. Even the non-enhanced sd7h15 would be better then either the 508 or 709.

FYI I think you can get this to work without gutting the system for a Vintage Air or Restomod AC, especially for what those companies are asking for them.