I have a brand new Gibson air conditioning/gas heating unit. The air conditioning part works fine. But the heating side won't.. What is happening is when the unit receives the signal to turn on, the unit fires up and heats up. Then when the fan turns on the flame stops. Can someone please help?

I have a brand new Gibson air conditioning/gas heating unit

Since this unit is new contact the contractor that did the install or contact a local Gibson dealer. You do not want to void the warranty by messing with it yourself.