94 Suburban AC intermittent

I have a ac compressor that doesn’t work all the time. I have read how voltage or low power can effect this. When mine does not start up, if you tap the end of the compressor with a rubber mallet, it engages and runs fine for an extended period. Am I dealing with a power supply issue, or could this just be a bad ac clutch?

sounds like clutch to me. Is not belt driven? How would it be a power supply problem?