[SOLVED] A blower motor question to stump the MASTERS! LOTS of PICS [SOLVED]
I pulled this motor out of our AC/Heating unit on the roof. It was completely siezed.
I called Universal Electric, now in Canada, and they directed me towards a direct replacement for this unit ( Grainger electric motor # 4KA37)
This is what the wiring looked like before I touched the unit:
3 wires- Yellow (allocated alone on the left) Red and a blue. Thats it.
The new unit from grainger came with 7 wires hanging from it.
2 brown ( Capacitor)
1 yellow (line?)
1 black (HI)
1 Blue (MED)
1 RED (LO)
1 Green (Ground)
Here is the schematic from the new 4KA37 Motor:
And a version I made for myself that eliminates the clockwise and counterclockwise rotation wires which are fine because the rotation is spot on.
NOW- I hooked the browns to the capacitor (Which is which does not matter I believe)--I grounded it with the green properly--I attached the yellow wire to where the yellow wire was on the original motor, allocated and insulated by itself on the left of the junction box.
Heres the tough part where I'm totally stumped. There are 3 terminals on the junction box atop the squirell cage left to fill. One black (hi), blue (med) and red (lo). The original motor as pictured above only had a blue and a red wire coming into it.
I have tried every concievable pattern of the red and blue wires in those three terminals and I only am getting 1 speed (Slow and not sufficient to move air through the house).
How on earth can I get the MAX speed from this 3 speed fan? The only "switch" I know of in the entire system is the thermostat which has "ON/AUTO" for the fan. Thats it. Any help and direction would be greatly appreciated.
Spat, I had a related with problem my old furnace motor
and took it down to what looks like a real hole in the wall
place that feels like it is still in the 1940's. It turns out
their business model is still 1940's but they still with
a staff of ~20 provide quick and low cost solutions for
almost any size consumer or industrial electric motor in
I took my motor in for analysis for which they charged ~25$
refundable if not repairable. Mine was not repairable,
but after a two day wait, I walked out of there with a
brand new replacement and a new belt for a little over
The service manager is immensely knowledgeable and
explained everything. I trust this place completely.
My old boss was an FAA Electrical Engineer who told
me that the FFA would (at least in the 60's) send
all their problem motors to Arbuckle
Is there n old capacitor behind that wire junction terminal.
Spat, I would take your new motor down to Arbuckle and have them analyze it to verify that that is indeed the correct replacement. They will use their own capacitor and verify the correct speed. It will cost you the service fee but then you will know for sure that you have the correct
Whatever happens let us know the result.
Thank you so very much for the advice. I will take both motors to the shop.
Yes, the capacitor is the original.
Take the old capacitor with you, it may be bad. You should always use a new capacitor when installing a new motor. Blow capacitor is one of the reasons a motor will run slow.
Everything else was right and the capacitor was fine as well. I did go to grainger and pick up a new one just to be safe. I figure it's a good $6 insurance policy. They were SO good at Arbuckle. Cant say enough good things.
I was equally impressed with Arbuckle. In our consumer oriented Internet age
it's easy to overlook those old time industrial shops that are still give mid-1990's
service backed up with years of experience.and a huge stock of parts.
When I took in my old split-phase motor, the motor internal wiring
insulation was so rotted that a new exact replacement was cheaper.
The new motor had a slightly different pulley which I asked about
since I thought they would just have used the original motor pulley.
The Manager showed me on the old motor the shiny area where the
where the rubber drive belt rode for 50+ years.
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