Hello,

Model no - AUD140C960J0

The blower on our furnace/AC that feed the house vent system has stopped working just yesterday. The AC compressor outside and it's fan still function fine when i set the thermostat to COol as does the gas heat if i turn the thermostat to Heating.

After doing some research, i open up the furnace and remove the capacitor to check it over with a multi meter. The capacitor is a GE 97F9004 15uf. I took it out and shorted the connectors with a wrench (rubber handles), no sparks flew. Tested it out on the multi meter and it returned 14.10uf.

I'm unsure if that reading is too low? And if it's not where to go next to troubleshoot?

Thanks,
Allan

 

Welcome to the forums.

That measurement is fine.
Check the blower motor for 120vAC. It should connect to a control board where you can make the test.

 

So i should hook the cap back up, turn the power back on at the breaker and set the thermostat to fan i'm assuming for it to be possibly getting 120vAC

 

Yes.... that is correct.
If you aren't sure what to check..... post a picture of the board. How-to-insert-pictures

 

Hooked everything back up, noticed some loose wiring so made sure all the wiring was fully on it's terminal - No difference.
Checked the blower wheel to make sure it's free moving and no wobble - Spins freely and no wobble.
Cap measures 14.10uf as mentioned before.

Circuit diagram (entire circuit and single of where i'm looking) and a couple pictures attached. From looking at that, i think i put black probe on the green wire (GND) that terminates to the side of the blower housing and then the red probe on the black wire (COOL-H) that connects to the board?

 

Additional information - While i was in the basement doing the above, i also took resistance readings from common White to the following

Red 3.3 ohms
Yellow 2.5 ohms
Blue 1.9 ohms
Black 1.6 ohms

The model number on the circuit too is 50A65-475

 

 

You've pretty much confirmed the motor is ok by the resistance readings. That board has timers on it that control the heating and cooling blower operations. In the link is a full description of how the board works but basically a short between R and G starts the blower in cooling mode. Usually the blower comes on immediately and is delayed off. In heating mode.... the blower is delayed coming on and delayed turning off.

Did you allow enough time for the furnace to heat up before the blower came on ?
Could be up to 180 seconds.

You can try a temporary jumper between R and G where the thermostat wires connect. Don't forget the blower door safety switch. If the door is open.... everything is dead. Just touch a wire jumper to those two terminals only. (leave wires connected)

To connect the blower motor directly to 120vAC....
The white wire is neutral and the black is cooling speed.
The white wire is neutral and the blue is heating speed.


Emerson climate control board

 

Ok so some further testing.. I ran both Heat and Cool cycles for 5 minutes each by setting the thermostat to like 60f and turning the system setting to Cool with the fan setting in Auto. I did the same for Heating by setting it to 80f, system to Heat and fan on Auto.

Cool - Set thermostat to Cool, heard the compressor turn on outside after 3 seconds and then nothing for the rest of the 5 minutes, no blower came on.
Heat - Set thermostat to Heat, the furnace in the basement was fully ignited after 28 seconds and the nothing for the rest of the 5 minutes, no blower came on.

Also tried to do some voltage readings, at the furnace i checked between G and C and i'm getting 26/27 vAC.
Between R and G i'm getting 0.1vAC. At the furnace I also put a jumper between R and G like in the pic below and the blower did not come on.

Still not sure i understand where to check for 120vAC, i did stick my probes in the back of the black and white wires from the blower and read nothing like 120vAC but unsure if i did that right..

How do i check if the tstat is actually sending the signal for the fan to come on?

At the thermostat, i removed the unit leaving just the wires behind it and jumped between R and Y and the AC compressor outside comes on. I jump between R and G to see if the blower will come on and it does not..

 

That is correct for the thermostat telling the blower to run.
Your problem is the control board.

If you want to try 120vAC directly to motor....... unplug the white and black motor wires from the board and temporarily connect a cord and plug to those two wires.

 

I just ordered a new board earlier, should be here on Saturday

 

Part arrived yesterday, switched it into the furnace and it works great again, thanks!

 

Good job. Thanks for letting us know how it went.