Hello again.... I must warn you in the strongest possible terms not to try and fix this yourself... and to call in a state licensed electrician.
Any loose wire can cause severely dangerous conditions depending on which wire it is...you can have an arc flash explosion.
187 volts between the two blacks is a low voltage
situation that can ruin your air conditioner.
If the loose wire is a white wire that would be why your lights are dimming. That can be dangerous as well. But not as dangerous as your working near the electric meter.
If a person does not fully understand the electrical engineering issues related to problems such as you are experiencing, and without such knowledge attempts to work on the electrical system.... instant *death is a common result.
Additionally family members using the appliances are at risk... these are serious issues and not at all a do it yourself type project.
Tell me which direction you are from the center of the nearest town or city, I will take a look and see what services are in your area....or you can call the local electrical utility company to investigate.
Let me know, we can go from there.