Without hearing the "noise" it is difficult to diagnose via internet; however, I can tell you that the 20 degF temperature difference is a good sign.
If the noise is at the outdoor unit, try to determine if it is the casing or something else. Sometimes the casing can rattle and/or vibrate that can cause a sound. Sounds can also come from refrigerant lines rubbing against the casing. Other noise sources at the outdoor unit are the fan motor, fan blade assembly, and compressor. You can remove one of the fan motor wires from the contactor, tape off the end, and start up the unit for a few seconds to see if the noise is still present. Then you can replace the wire and remove the compressor wires from the contactor and repeat the test. This will help you determine where the sound is coming from. If the sound is coming from your indoor unitl, the most common sources are loose tape, Blower wheel, blower motor, or blower housing. Also look for loose panels.
Without being onsite with toolbox in hand and being able to actually hear the sound, I hope you find this information to be helpful to you moving forward. :-)
Answers & Comments
Without hearing the "noise" it is difficult to diagnose via internet; however, I can tell you that the 20 degF temperature difference is a good sign.
If the noise is at the outdoor unit, try to determine if it is the casing or something else. Sometimes the casing can rattle and/or vibrate that can cause a sound. Sounds can also come from refrigerant lines rubbing against the casing. Other noise sources at the outdoor unit are the fan motor, fan blade assembly, and compressor. You can remove one of the fan motor wires from the contactor, tape off the end, and start up the unit for a few seconds to see if the noise is still present. Then you can replace the wire and remove the compressor wires from the contactor and repeat the test. This will help you determine where the sound is coming from.
If the sound is coming from your indoor unitl, the most common sources are loose tape, Blower wheel, blower motor, or blower housing. Also look for loose panels.
Without being onsite with toolbox in hand and being able to actually hear the sound, I hope you find this information to be helpful to you moving forward. :-)