Question about blower speeds


Old 07-16-10, 09:09 AM
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Question about blower speeds

I just replaced the 4 speed blower motor on a 25 year old unit.

Every time I looked online for reassurance about what I was doing, I saw mention of capacitors. This unit had none. Made me feel like I was missing something. I guess that is just how it was done back when this place was built.

The part was quite expensive, and took trips to many stores this morning, but it seems to be working well right now.

One thing struck me as odd. The new blower said that yellow was medium low and blue was medium high. This seems different than normal. I spliced the wires to match their colors, and now #2 on the plug is actually my medium low. Should I have done this differently? Do I run the risk of damaging anything? The wiring diagram says to plug black into #1 or high, which was normal, and the red wire/low into medium/low or number #3. Previously #2 and #4 were not used on the connector. Should I still have put in #3 despite it actually being medium hi now?

My other question is, when does the speed change? It always seemed to run at a constant speed. How can I tell if its running high or low? Well, I suppose a multimeter can do that last part for me.

Any help and info would be appreciated.


One more thing, do I need to oil a new motor with sleeve bearings? The paperwork says I dont need to with ball bearings, but nothing about sleeve bearings.

Last edited by ericbee; 07-16-10 at 09:44 AM.
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Old 07-16-10, 05:12 PM
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Blower Speeds

Normally the blower speed wires are in order (either low to high or high to low) but this isn't carved in stone. For simplicity sake I would switch the two middle wires regardless of color.

I would put the heating speed (red wire) on med-low if that is where it was on the old motor.

The blower motor changes speed depending upon in which mode (heating or cooling) the furnace is operating.
Old 07-20-10, 06:45 AM
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Well, it ran fine all weekend with that wiring and with no oil. I guess I will just wait the 2 years to oil it.

The old one was connected to hi and medium low, which is where it is now, just that the wires where in C,1, and 3 before. Now its C, 1, and 2 because I matched the colors despite them being different.

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