My furnace will not come on . All I hear is a click when I turn it on. The LED is indicating that "pressure switch problem". How can I check to see if that is the problem. When the thermostat is on the ON position the fan or blower will run but no heat. Can you help

You should hear the inducer motor running(Exhaust vent motor). If not that's the reason for the pressure switch problem. The inducer motor kicks on first and the closes the pressure switch.