The outside fan comes on and every few minutes the contactor makes a humming sound. The compressor is not coming on. I think that the dual capacitor is working OK. Not sure about the low pressure switch...

Moved from Electrical to HVAC.

These guys are so much more knowledgeable about AC that us electricians.

Sounds like either the compressor is not starting but trying to start. Could be capasitor, or a burnt wire. Or compressor itself