No Heat Service Call T-Stat Satisfied Upon Arrival

On this no heat service call, the thermostat is set for 74, and the room is 74. When everybody first got to work the heat wouldn’t catch up it was at 62 for a while. I got up to the unit and turn it on. The unit fires up. I decided to check the flame sensor, make sure the flame sensor not dirty. The Flame sense current is high enough not to be creating any issues. The unit is flashing a fault code. I noticed that the blower motor wasn’t running. I take the door off to find a broken belt. I run out and get the correct belt, install about and test the operation of the unit. Unit fires up, does not overheat, and was operating correctly.