go to forum achrcives and search for POA There are a few articles to read

https://autoacforum.com/messageview.cfm ... adid=16311

Unless you use different manifolds for different refrigerants, yes clear out the gauges and zero them out for accuracy. You should not mix oils either. It is best to have a different set for different refrigerants.

if you think the compressor is locked up unplug it and put a lamp in its place. Do not use a 60 amp fuse in place of a 30 amp. Too much of a difference and you can let the magic smoke out.

The input and output lines of the evaporator should be close in respect to temperature. If they are cold, then start looking at a reheat problem. Clamp off the heater hose or disconnect the heater core. The engine needs to be at 1500 rpm to 2000rpm. If the lines are cold, it is possible the evaporat...

There should be a sticker under the hood indicating the correct refrigerant charge. Go by that and not any chart.

well if you use F instead of C you may get more answers. At idle you're getting about 39degrees and at running 49 degrees right? Usually it is the other way around due to more airflow across the condenser. You may have a marginal control valve if the compressor uses one. If you have to recharge the ...

If you think R12 is expensive, wait until you price R1234YF. R1234YF is being used on a lot of new vehicles.

Keep it R12

you need to put some refrigerant ( 1or 2 oz) and nitrogen. Use an electronic sniffer to find your leak. Do not forget to check your gauge set.

Did you disconnect the hoses from the fittings? You may have a leaky coil and need a sniffer (electronic) and some refrigerant and N2.