Black cap on accumulator if you have a regular hose end

So now you have converted the system to a cycling clutch system. A6 compressors have a rather small clutch contact area. They were not meant to cycle. GM tried that and found that they had to increase the clutch area; hence, the birth of the R4 compressor. we all know how they held up. You adjusted ...

You need to run the engine at 1500 rpm, doors/windows open, max fan speed/max cool; then give it time to stabilize and post your temps and pressures.
Make sure the radiator is clean. I do not have a schematic or this vehicle to check the control system.

If it cycles every 6 to 10 seconds, your clutch won't last very long.

you could be a few ounces low on refrigerant. Compressor does not put out as much at idle as when cruising. I would add a few oz of refrigerant.

Mist the condenser with a water hose. If the high side drops like a rock, you have condenser, air low over the condenser problems. Whaen the high side goes down so will the low side. An area to check is the cooling fan.

Measure the inlet tube and outlet tube of the evaporator. The outlet should be slightly colder. What I would do is reduce the refrigerant amount slightly. You may be slightly over charged. I would also be looking at your high side. Are all the air shields installed so the air flow gets across the co...

monitor the voltage to the compressor clutch. If hook up a small lamp and run it into the cab. You also may have a marginal clutch gap.

Well for one reason is the systems today use small amounts of refrigerant. Some use less than 2 lbs. So if your charge is 4 oz off because you used PSI and temps,your % of error is higher. Also, the older systems had driers that stored extra refrigerant for TXV's. Systems today use orfices and flood...

Mastercool used to have a book explaining the steps. Tim at AC Kits sold them. i have not seen them in a while so I do not know if they are still available.