My central heat/air won't run. The breaker has nothing wrong with it. There is current at the heat exchangers. There is no current at the thermostat, and I changed the thermostat today. The a/c was working fine yesterday and it just quit. What should I look for next? I suspect some sort of internal breaker or other thing that is responsible for putting dc current to the thermostat.
No electricity to the thermostat of my central heat/air?
There may be a small fuse on the control board. It should look like an automotive fuse. Either 3 or 5 amps. Replace it if it is blown. If it continues to blow, this indicates a problem with the low voltage circuit. FYI, a/c current should be at the thermostat not dc. So make sure your meter is on the correct setting. Should be getting around 24 V a/c.
