I have an Emerson (4 Speed) direct drive blower for my gas furnace. What is the process (wire color codes) to change speeds on the blower. (I have a red, black and yellow wires taped off in the wire loom) I want to cut the speed down from Med/High to Low/High. Thank you very much

• Black: Ground
• Blue/White: Power (12V) from HVAC control unit to blower relay
• Blue/Yellow: Power (12V) from blower relay to blower motor
• Blue/Black: Ground from blower motor to chassis

psc motors have 4 speeds each colored black blue yellow red and white. there are speed taps on the board labeled heat, cool, even heat/cool and usually Park or M1 male spade fittings for the unused speeds. on the door will tell you speed chart by wire color ie black is high and red is low speed. newer models ask you not to use red for heat. to change speeds is by changing wires and their system mode taps. (beware the push release female end locks into the board) If using black for both and there is a heat/cool tap make sure that the separate taps cool or heat are empty, or motor will receive 120 volts twice. 1 thing to remember a 3.5 ton blower with a 2 ton air cond. wouldn't want to use black too much air flow.
If you have a variable speed its all in the bible for a manual and which dip switch position for cfm air flow.

Gas valve should only have a couple of wires...24 Volt & common. the blower will use one speed on a gas furnace & a common. If you have AC or a fan switch on your thermostat, then the high speed will also be connected on the blower.

All York/JCI thermostats made by Venstar

The setup is probably incomplete. Did you configure the thermostat for a 2 stage heat pump? The heat pump should have a thermostat wire connected to R, C, Y1, Y2, and O, that makes 5 wires. I suspect you are only using first stage compression and or first stage blower speed.

Your homes ductwork needs to be balanced. Get someone that can read airflow...personally I use a balometer made by alnor. Ir is probably not a fan speed issue, but if you want to check the speeds of the fan, it should be a 3 or 4 speed motor. Look @ what color motor lead is attached to heat terminal on the circuit board, and if necessary, change to the higher speed motor lead that is not use (on an unused terminal)

The only way to really tell if the blower is set to high is to look at the control board inside the furnace and see how it is hooked up. You will have either a 3 speed or 4 speed blower motor, more than likely a 4. These are Hi, Med Hi, Med Low, Low. Each speed has its own color and if the motor has ever been changed, it could be different from factory diagrams. The most common colors/speeds are:

Black- Hi
Blue- Med Hi
Orange- Med Low
Red- Low

You could have different colors but they will be close. If it's an aftermarket motor, the speeds will be listed on the motor itself, but very difficult to get to sometimes. On the board, you should have terminals marked, COOL, HEAT, PARK, PARK. You hook what speed you want for Cool and Heat and put the other 1 or 2 wires on Park.

Again, these might not be exact, but these are the basics and they usually don't deviate from them to much unless it's a 95% furnace or such. If you do have the diagram for the furnace, you will be able to find everything with no problem now that you have the basics. Also keep in mind that you will have a Common wire from the motor that hooks to Com. terminals on the board. Hope this helps and good look!

how about when the fan is in the on position?

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I would probably use a furnace for the correct application. However some motors do have a reverse speed connection. Besides the blower speed taps,
capacitor wires and the nuetral wire. There are two wire sets that you can switch that can do this if your blower motor is equipped.

You might experience some airflow problems, probably a lack of airflow, if the furnace was installed
as an upflow model instead of a counterflow.

Motor speeds on the blower are always remember black is high, blue in med. and red is low sometimes blowers are 4 speeds but the main colors are the black blue and red. Now where to change locate the wires coming from blower to a box or control board. control board has setting for heating and cooling speeds for the blower. You might see blue on heating which would be medium speed so take the red off park terminal and change places with the blue. Now if you have a fan control switch it looks like a dail in the middle of the furnace with numbers on the face with pointers set at the numbers. follow the wires from there to the electrical box and open box. find color of blower and switch be sure to cap off the wire you change. Wire nut would be good.