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View Full Version : Recently replaced furnace control board, now blower will not come on with AC.


STL_Jeff
Feb 18, 2011, 02:20 PM
I recently replaced a 50A50-110 control board (Comfortmaker) with a White-Rodgers universal 50M56U-843 control board and the furnace worked fine throughout the winter. However, I just tried the AC for the first time this season and the blower will not come on with the AC. The compressor and outside fan seem to come on as they should. Could I have a couple wires hooked up incorrectly on the conrol board? Any help would be greatly apprectiated. Thanks in advance.

T-Top
Feb 18, 2011, 06:40 PM
It's a three speed blower control make sure you have a blower speed wire on the cool term on the board. Make sure you have a good connection on the G terminal on the control board(thermostat wire) from the thermostat.

STL_Jeff
Feb 18, 2011, 11:03 PM
I recently replaced a 50A50-110 control board (Comfortmaker) with a White-Rodgers universal 50M56U-843 control board and the furnace worked fine throughout the winter. However, I just tried the AC for the first time this season and the blower will not come on with the AC. The compressor and outside fan seem to come on as they should. Could I have a couple wires hooked up incorrectly on the conrol board? Any help would be greatly apprectiated. Thanks in advance.It's a three speed blower control make sure you have a blower speed wire on the cool term on the board. Make sure you have a good connection on the G terminal on the control board(thermostat wire) from the thermostat.

STL_Jeff
Feb 18, 2011, 11:07 PM
Well I'm VERY new to forums, so I hope I update this the proper way. Thank you T-Top, it seems as if you were correct. I had hooked the new control board up exactly as the old one was hooked up. The problem was, there was a red wire coming from the blower that was hooked to "Park" on the old control board, but needed to be hooked to "Low Heat" on the new control board. I'm guessing this is because this new board has the ability to control multiple speed blowers and my old blower is just one speed? Whichever reason it is, it works and I'm happy. More importantly, the old lady's happy:) Thanks a lot for your help, it's much appreciated!