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airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8030
Experience:  Furnace, A/C and heat pump specialist.
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My blower motor doesn't work. i have been trying to diagnose

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my blower motor doesn't work. i have been trying to diagnose it my self but I can;t seem to figure out the wire colors. they don't match any colors in any tutorials online.

Hello, one minute while I get some information together.

Hello and thanks for using this service! If you are a JA Member I would like to personally thank you and welcome you back! I am Appliance Guru an extremely experienced tech on the site and I try to get to as many customers as I can. NOTE it takes time for me to type research and add links so please wait for me to respond back I can only do this so fast. Secondly, I do not know your skill level so please try and let me know if I am going beyond your knowledge or comfort zone thanks! I strive for a 5 star rating from everyone especially our JA members.

Does the motor hum or do anything?

Customer: replied 2 months ago.
my comfort level or skill level is basically 0 when it comes to electricity. but quick to learn, I just need clear concise and step by step instruction and information.The motor does nothing. Here is the scenario that brought me here.
The Air filter was pretty dirty from a summer of use with out changing it. The blower was still working when I finally got a chance to change the filter. I changed it and the blower kept working as normal... only for a day. Then I went into the attic and pulled the disconnect fuse box and turned the power off from the breaker panel. I opened the furnace and gave the motor a spin with my hand just to make sure nothing was blocking it, it moved smoothly. I turned all the power back on and then set the t-stat to "fan on" and voila! the blower came back on and it ran.. only for a day. The next time we needed the fan to blow. it did not work. I repeated what I did the last time and still nothing.The only hum I hear is of, what I would call electrical hum from where all the wires are. There is no hum coming from the motor.

OK this sounds like a bad connection to the motor or at the board itself. Disconnect the wiring from the blower motor at the board then reconnect it and try it, if it is working even briefly I would say you have a bad connection on the board itself. This could be a bad solder joint, bad really or just a bad board. That is what this is all sounding like though.

All I ask is please use the Star Rating Link at the top of your page before leaving, that is the only way I am credited through the site, tips are appreciated.

Customer: replied 2 months ago.
1. How do I fix that connection?
2. Where is the bad relay? ( you wrote bad "really" but I assume you meant relay)
3. What does the relay look like?
I have a multimeter to check for wiring issues.4. I would assume a bad board would mean nothing works, correct?
5. The t-stat turns the ac compressor on just fine and that runs through the board too correct?would pictures help?
Customer: replied 2 months ago.

Do you have voltage from Black to Yellow at the motor?

Customer: replied 2 months ago.
how do I check that?
Customer: replied 2 months ago.
I put the meter to just the black and yellow. it reads: 495 ohms / 0 vdc / .004 vac / and no continuity.
Customer: replied 2 months ago.
any new input?

If there is no voltage there you need to replace the board.

All I ask is please use the Star Rating Link at the top of your page before leaving, that is the only way I am credited through the site, tips are appreciated.

Customer: replied 2 months ago.
I want to give you a high rating but I feel like you haven't helped me at all.You have told WHAT I should do but not HOW to do it.I am a beginner at this but I have a basic knowledge of some things. If I don't know I will let you know and I expect a clear explanation.I checked the black and yellow wires for voltage while it was hot, I assume that's what you neef to do to measure voltage. The measurements I gave you previously were from the wires coming off the motor, no power running through them.I switched the motor speed by moving the blue cable to the 1 position and got it to start running. But again, after a day, the fan fails to turn on from the tstat.

I am sorry let me get you another expert I have helped you get to the issue at hand I can not be on site doing the job and with working for free the whole time here with zero pay I need to get you with another expert on this. You have to realize we are not paid anything at all until a good rating is given so with the time spent on this and with you having such limited experience I doubt I will get a good rating. Just stand by for another expert to pick this up.

Good morning.My name is ***** ***** different expert.I understand you feeling like you should pay expert and give a 5 star rating just for replying and begging. Please do not rate answer until we are done.

Your unit has what is called an ECM variable speed. A lot of people do not understand how these motors work.It is very easy when not paying for parts to just tell people replace board or replace the motor,but without troubleshooting, you are guessing at most.

Your motor is High voltage powered but low voltage controlled by the bell on the end of the motor.

The first step in troubleshooting is to see if we are getting both high voltage power to motor and low voltage on demand.

I am attaching a drawing showing where to check for power.

We should have 240v to motor at all times between the Yellow and black at transformer as shown in this drawing.

On call for ac or fan, we should get 24 volts ac between brown (common) and Blue

On call for Heat we should get 24 volts ac between brown (common and white).

You can follow the wires to a terminal where they attach so you do not have to cut the wire.

I will note that the most common thing on these units that fail is the actual control bell on the end of the motor but lets not guess.

If we get both 240 and 24 volts, we will know the bell is the problem.If not we will go from here.

Customer: replied 2 months ago.
Great, thank you for your thorough drawing. I am going to check those voltages now and get back to you
Customer: replied 2 months ago.
brown blue = 29.06 vac
brown white = 28.97 vac
black yellow = 247.5 vacSo it seems the bell is the problem. Whats next boss??

That is correct we are getting proper voltage but bell controller is not responding.Some of these motors have a replacable bell and some you have to replace entire motor with bell.

Look on motor and bell and get model numbers so we can Google to determine if we can get just the bell.

airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8030
Experience: Furnace, A/C and heat pump specialist.
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