New blower motor in air handler won't start

Problems related to residential installations.

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Chrisveach1
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New blower motor in air handler won't start

Post by Chrisveach1 » Fri Jan 09, 2015 12:40 pm

I changed out the capacitor and blower motor in my Lennox/Duncan's hvac, and when I put power to it, motor would not start. The specs on new motor are exactly the same as old. I don't have a heat pump, and I heard some clicking from the board. The motor plugs into the board directly with no relay. Everything else works so I don't think the board is bad. Checked tsat and tried jumping red and green wires. Blower still wouldn't start. Any ideas? It's freezing and I have a small child.

Freon
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- New blower motor in air handler won't start

Post by Freon » Sat Jan 10, 2015 1:34 pm

I am assuming you're referring to the main blower motor that circulates air in your house.

Did you try setting at the thermostat the FAN to ON (not AUTO)? That is like jumping red and green but try it anyway.

If that still doesn't work, unplug the motor plug from the control board. Make sure on the control board where the motor plug is soldered you can find the common terminal. It should be where the white wire from the motor side plugs into, BUT DOUBLE CHECK. Refer to the schematic diagram located on the furnace. With the thermostat set to FAN - ON, check for 120 (240?) volts AC between the common terminal of the plug on the control board and each of the other terminals where the motor wires would plug into. One of those terminal pairs (white+?) should give you a voltage reading.

If there is no voltage then tell us how the old motor died. Check the control board for signs of a fried component. The damage could be only to the motor power part of the control board, usually a relay.

Chrisveach1
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- New blower motor in air handler won't start

Post by Chrisveach1 » Sat Jan 10, 2015 6:16 pm

Thanks for responding. I have already tried the tstat on "on" and nothing. Tried jumping red and green wires at tstat with nothing. Tried jumping red and green at board with no result. Switched heat and cool connections at board from motor to try and see if fan speed was issue. Nothing. Looked at the back of the board and see no obvious burn/damage. I have no volt meter. My buddy is hvac guy but hasn't shown up to help yet. The motor used to make a loud buzz and start, then would only start by hand(kick start). Replaced capacitor and it worked for a day and then died. After putting in new motor, no loud buzz and no start. I hear a loud click from what is transformer near board. Motor plugs directly into board(no relay). Iwhen I put in new motor, I left original wires running to board and used spade connectors to join new wires from new motor to old wires going to board. Without being able to check volts/current yet, any ideas?

Chrisveach1
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- New blower motor in air handler won't start

Post by Chrisveach1 » Sat Jan 10, 2015 6:28 pm

Sorry, I'm not sure about the motor plug. The wires are as follows. Red is motor low and runs to board in slot labeled "unused. Blue wire goes to board terminal labeled heat and is motor medium. Black is motor high and plugs into board terminal labeled cool. Common wire runs to wire nut that ties 4 wires together from various places. The flash code is "calling for heat" I tested the pressure switch and it seems good. Everything else in furnace is working, but I don't want to break the fan limit switch but trying to turn the fan on over and over and lighting the furnace.

Freon
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- New blower motor in air handler won't start

Post by Freon » Sun Jan 11, 2015 2:11 pm

The loud click could be the relay. It will be mounted on the board with a trace going to the plug on the board where the motor plugs into. You really need a voltmeter to see if there's voltage at the plug on the board (with the plug going to the motor removed). If you have 120 volts AC at the board (between black and common) then you know the relay is OK. If there's no voltage then you know it's a relay issue or a 120 volt power to the relay issue.

The relays are usually small black cubes. On a call for heat the furnace will run for a minute or two before the blower heat relay energizes. There could be 2 relays, one for the Heat and one for both Cool and Fan-On. The fact you can't get either the Heat or Fan-On to energize the blower motor makes me wonder about the 120 volts the relays are switching on/off. Again you'll need a voltmeter. Any fuses on the board?

Chrisveach1
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- New blower motor in air handler won't start

Post by Chrisveach1 » Sun Jan 11, 2015 2:25 pm

White common wire runs from line in and is wire nutter to 3other lines. One runs to blower motor, one to inducer blower motor and one to transformer. There is one relay box. I see the black wire running from the relay to the board. Right next to it there is a terminal with a black wire running back toward the motor. I assume that is the power you mentioned. I have a voltmeter now, just wondering where to hook up to the white common, since it doesn't plug directly to the board, but is spliced into the other wired I mentioned. The only common wire hooked directly to the board is at tstat control

Chrisveach1
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- New blower motor in air handler won't start

Post by Chrisveach1 » Sun Jan 11, 2015 2:31 pm

One 5 amp fuse btw and it looks intact. I have a spade connection after the 4 wire splice that also goes to relay. White wire, assuming common. Should I test that to the board terminal?

Chrisveach1
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- New blower motor in air handler won't start

Post by Chrisveach1 » Sun Jan 11, 2015 2:38 pm

The box the trace wire is plugged into is labeled transformer on diagram. It also has common wire and a yellow and blue wire from other side. These are 24v wires to board.

Chrisveach1
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- New blower motor in air handler won't start

Post by Chrisveach1 » Sun Jan 11, 2015 2:46 pm

Pulled the motor wire and is jumpered to the spade connector running to tformer. 2 wires into one plug.

Chrisveach1
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- New blower motor in air handler won't start

Post by Chrisveach1 » Sun Jan 11, 2015 3:10 pm

I tried to test the motor wire connection on board to first wire nut connection from line in common white. Not sure if it should read or not the way I tried. Thrown for a loop with the dual connection. Thanks for getting back to me, I know it's playoff weekend and all.

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