Have a old GE central a/c heater. It is cooling great but come to find out the heater is not turning on. The pilot is on, thermostat raised all the way up. No response. Switch back to a/c, lower thermo and blower kicks on and begins cooling.

Have you had it serviced for the season? Heating units should be service EVERY season. Could be a bad ignitor, thermostat, no gas flow(A/C uses no gas). Best to call a service tech for this. Good Luck.