Hi I'm trying to help my uncle get his coleman 7900 series furnace working.. he told me that about 2 years ago they had a power serge and it hasn't worked sense then. What could be the problem? :confused:

Almost anything could be a problem. Start at the furnace and check to be sure it is getting 120 volts to the furnace itself. Then check to make sure the low voltage transformer is supplying 24 volts to the control circuit.

You might post the complete model number for more specific ideas.