Furnace Control Board Has No Power

Measure from r to w.

Furnace control board has no power.

If you have 24 volts and no light on board. Make sure the 110v power switch at the air handler furnace has not been turned off then see if the fuse on the board at the air handler is not blown automotive type then there is a safety switch. It is possible that the problem could stem from your electrical system rather than the furnace itself but your hvac system is the best place to start. Just went thru the flow charts from rheem on that furnace.

Power up transformer cool mode works blower stays on after temp is reached. I can run the fan on continuously but when i put the heat to on on the t stat the 5 amp fuse on the control board lh33wp003a in the furnace blows. The electric furnace transformer may be failing causing the system to short. Don t forget when the blower door is open.

You should see 24vac. A model number of the furnace would be helpful too. The ac power is disconnected. In some cases this will be line voltage and in other cases the board will get its power from the control transformer.

The sequence is like this. You should see 24vac. Check for 24 volts to board from transformer. If your building s electrical system supports 120 volts your furnace needs a transformer to convert to the correct voltage to run the controls ignition and timers.

First make sure you have power to the board. If your electric furnace is blowing a fuse repeatedly when turning on your first step should be to call in an experienced hvac repair professional. Changed control board in gas furnace new board has no power to transformer blower motor lead on cool terminal hot all the time all the safety switches ohm out. Either way check to make sure you have the proper input voltage to the board.

Furnace control board fuse keeps blowing 1 answers hi i have a carrier furnace 48gs 036090311tp with a honeywell t8401c thermostat. You have bad board replace it. With the stat in off mode. Next you want to check the output and this is a little more involved than the previous step.

What would cause electric furnace circuit board to fail. If so it will need to be replaced.