I know this means low voltage but how do you fix it? Is it the unit or is it the power coming to your house?

You need to go to Home Depot, Lowe's, or Radio Shack and buy a good digital multimeter. There is no other way to measure voltage and diagnose any appliance. I meter is something that is indispensable in a home. You use it to test all kinds of things because you cannot see voltage without a meter, nor can you see if a circuit, switch, fuse, or safety is open with your eyes alone. Her are directions: https://dl.dropboxusercontent.com/u/...e%20Manual.pdf
https://dl.dropboxusercontent.com/u/...20Handbook.pdf
https://dl.dropboxusercontent.com/u/...e%20Manual.pdf
https://dl.dropboxusercontent.com/u/...Electronic.pdf