Make sure the electric cooling fan/s are working and the condensor face is clean of bugs and dirt. The difference between high and low pressure w/ a low charge suggests your compressor may not be performing to spec.

Make sure your receiver/drier is not causing a partial blockaage (look for colds spots around receiver/drier). If a blockage were present, you would have low high side pressures since high pressure tap is downstream of receiver/drier.

My guess is a tired compressor.

good luck

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