Your first test should be low fan circuit test. If that passes and the low fan is still not coming on with hot ambient, you are most likely still low of refrig.
If the high pressure sw cuts-out the compressor while low fan is operating, you may be slightly overcharged. Buit if low fan is not working, the comp can cut-out b/c the high pressure is not being checked by low fan..[ that is what the low fan does]
..so, you can see where low fan circuit integrity test has priority over all other test..That is the first test to be done b/c it effects all high side pressure conditions more than any other faulty condition.
Changing a system w/o having low fan circuit in operating condition is a waste of time and refrigerant.

These are just quick check diy things to look for for basic diagnosis..actual charge shoud be done by weight or, in the case af topping, with gauges in comparison to ambient temps.
Test the low fan circuit first.

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