I have a luxaire furnace TM9X *MP series and the blower speed on heat is very high. On the control board, the Black wire is connected to the Heat pin, the Blue is connected to Hi Cool, Gray to Lo cool, Red to ground and yellow to Park. The wiring diagram indicates the following:
Black - high
Blue - Medium high
gray - medium
yellow - medium low
red - low
The Blower speed chart has the following:
Input | CFM | Heat | Hi-Cool | Lo Cool | G | Park
60 | 1200 | blu | blk | gry |Red| Yel
80 | 1200 | blu | blk | gry |Red| Yel
80 | 1600 | blu | blk | gry |Red| Yel
100 | 1600 | blk | blu | gry |Red| Yel
100 | 2000 | blu | blk | gry |Red| Yel
120 | 2000 | blu | blk | gry |Red| Yel
Am I correct in assuming that if I want the blower speed to be on medium Hi, I should connect the Blue to the Heat pin, and the Black to the Hi Cool Pin?
Also, the Blower speed chart does not have anything but blue or black listed in the Heat column - is this saying that I can't have medium speed (gray wire connected to the heat pin in the contol board) on this furnace?
If not interchanging the wires will change the fan speed, care must be taken that your differential temperatures through the heat exchanger remain within the design specification of the equipment design.
For instance if it says you the furnace tag, 45-60 the ideal would be at return temp at XX supply temp (about 3-4 ft down stream of furnace in main duct) would be xx + 54*F.
You will have to change it back when you get into the cooling season, or else you risk freezing your evap coil.
When its all said and done there is usually more said than done