You could not pick a worse vehicle to convert to 134a. Do not convert it. '71 is a POA valve system with the A6 compressor, and had no LPCO. I've read that the POA valve can be re-calibrated for 134a. Will A6 compressor not work with 134a? I've tried to keep it as the original R12'refridgerant but ...

The 71 vette drier must be changed to accept R134a. This is probably a POA system so the POA will need to be set for R134a. Vettes were not good vehicles for conversions. I would stick with keeping it R12.

You can add R134 and use it to leak check. The problem is that you should be recovering the r134 after you leak check and "Joe Homeowner" usually does not have recovery equipment.

Just viewed your video. Loks like fan clutch to me.

Your original post stated that you jumped the switch and compressor kept running. Get both gauges installed and then come back with info.

you can not determine if the high side is high or not until the compressor runs all the time.

That may indicate that you're trying to ruin your compressor. You need to monitor both lo and hi sides.

you're probably low on refrigerant. Recover and recharge to spec. Doors and windows open, rpm 1500.

Condensers go bad when the compressor goes bad sometimes. The parts in the compressor gets into condensers and plugs them up. Sometimes a rock can puncture a condenser. If the fans do not come on with the AC, try the relay. I think Autozone will show you where the relay is located. with the summer m...

I am sorry you have run into a tech that apparently is not well versed on repairing your vehicle. If in fact the AC works when you mist the condenser with a water hose, that proves it is an airflow problem across the condenser. The condenser is responsible to extract the heat out of the refrigerant ...