UHA S TANDARD U NIT H EATER I NSTALLATION O PERATION AND SERVICE MANUAL36 of 59Figure 16:LED INDICATION FAULT MODESlow Flash Normal Operation - No call for heat.Fast Flash Normal Operation - Call for heat.2 Flashes Ignition Lockout - No flame detected.3 Flashes Airflow Fault - Pressure switch open or closed.4 Flashes Temperature Limit Switch Open5 Flashes Flame Sense Error - Gas valve not energized.Steady On Internal Control FailureLED Diagnostic Codes