New Guy Hasn't Eaten

I got a male mojave two weeks ago, I tried offering him a live rat (which is what he had been on before) and he didnt eat it. I put it in his enclosure with the lights off. The temps are good too, 90 degree basking spot with about 80 degree ambiant.

How old is he? What size rat?

How old is he? Has he been handled alot or left alone to settle in? Try leaving him alone for a week and try again at night.

Describe his husbandry please. (cage size and age especially)

He is an 08. Im not sure of the weight but he is 30 inches long. The humidity is lower than it should be cause the AC keeps the house dry. My room is a little more humid though with the fish tanks. I handled him very little the first week but more the second week. Should I try again today? Lights on or off? Oh yeah, he is in a 10 gallon tank.

What are the temperatures like, cold side/warm side? You need to try and do something about the humidity like misting lightly each day. You also need to leave it completely alone for at least a week once you perfect the temperatures and humidity. This way it can settle in without any stress. The feed it and leave it alone for another 2 days. Then you can start handling it a little at a time.

Should I offer him the rat every day to see if he wants it?

Make sure the rodent is of the proper size. The width of its body, around the hips, should be slightly smaller than the thickest part of your snake.
Try feeding it at night. Only have enough light in the room to make it so you can see what you are doing.
Offer the prey and leave it alone for 10 minutes or so. If he doesn't take it, remove the prey and wait for the next feed day. Try your best not to handle the snake until it starts to feed for you.
If your husbandry techniques are spot on you should have a good feeder on your hands in a few attempts.