I have an American Standard Model#cdb100a945d3. Overnight it quit coming on. I have chked the code on the control bd and it is giving just 1 slow flash which indicates normal operation with no call for heat. The temp in the house is 64 and I have the thermostat set on 72. I have turned the t-stat all the way up & still & turned the unit on and off and still no response. The thermostat is a Climate Technology digital thermostat. Is this a problem with the thermostat or where should I start looking?? Thanks
Make sure the thermostat has not been switched to something other than a heat mode or that you have dead batterys.
To test the thermostat, turn off power, pull off the thermostat sub cover and jumper or connect together (R & W). Turn power back on.
If furnace comes on ...Faulty or miss set thermostat.
You can also do the same thing where the thermostat wires connected to the furnace board to check both the thermostat & the wiring circuit.
Turn off power, remove stat lines R & W, put jumper from board connection R to W. turn power back on. If the furnace runs it will be a faulty thermostat, stat wiring or their connections.