Furnace Control Board Has No Power

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.

Furnace control board has no power.

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. What would cause electric furnace circuit board to fail. 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. A model number of the furnace would be helpful too.

Either way check to make sure you have the proper input voltage to the board. Just went thru the flow charts from rheem on that furnace. The ac power is disconnected. You have bad board replace it.

Next you want to check the output and this is a little more involved than the previous step. Don t forget when the blower door is open. With the stat in off mode. The electric furnace transformer may be failing causing the system to short.

If you have 24 volts and no light on board. If so it will need to be replaced. 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. Measure from r to w.

You should see 24vac. Measure from r to c at the control board. First make sure you have power to the board. The sequence is like this.

Check for 24 volts to board from transformer. Furnace control board fuse keeps blowing 1 answers hi i have a carrier furnace 48gs 036090311tp with a honeywell t8401c thermostat. You should see 24vac. Fan only operation is running.

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. In some cases this will be line voltage and in other cases the board will get its power from the control transformer.