Nordyne Gas Furnace: G51MP Re: Furnace Lockout Codes Furnace Control Board Fault Conditions DS1 (Red or Green) DS2 (Green) Description Simultaneous Slow Flash Power On - No Call For Heat Simultaneous Fast Flash Normal Operation - Call For Heat ...

Lennox Gas Furnaces: G51MP Re: Pressure Switch Fault Diagnostic Light Sequence: DS1 (Red or Green) = Off, DS2 (Green) = Slow Flash ►There are two Differential-Pressure switches wired in series. A Pressure Switch Fault is caused by one of the following: Either Pressure Switch contacts...