The Virtual Repairman's Appliance Help

[billnc]

Oh the trouble that happens when money is tight.

I have a Trane gas pack and the indoor blower motor stopped working. I had a prepaid service call in my pocket from my local
HVAC guy. He came out and determined that the indoor blower motor was fried. I saw the capacitor reading ok, so I had confidence that he was telling me the truth.

It was to cost $410 to replace the blower motor. About the going rate, but I simply didn't have it.

I knew where the local Trane parts dealer was, so I got the proper numbers and came home with the right motor.

I got the old motor out, got the new motor in, but here is where the plot thickens.

The old motor had 5 wires. These included
#1 A ground wire
#2 A purple wire going to the capacitor
#3 A brown wire going to the other terminal of the capacitor
#4 A red wire going to a 4 post terminal of some sort where 3 other wires are attached.
#5 A black wire which was taped off & not attached.

As best I can tell the red & black wires were for fan speed choices. The schematic showed that either the red or the black could be attached to the terminal.

The new motor has 8 wires. These include
#1 A ground wire
#2 & #3 - two same color wires which are to go to the capacitor
#4 thu #7 - Red, black, yellow, blue wires which are various speed wires
#8 A White Common wire

I was guessing to attach the black wire (High speed) to the post where the former red wire was attached.

I have no idea where to attach the White common wire. The old motor didn't have one.

I can't get the thing to work and I know my HVAC guy will STILL want $400, even though I've already bought the new $100 motor.

In fooling around with the wiring, the unit clicked once, and now there doesn't seem to be any power available at all. I can't find a tripped circuit breaker & I didn' t know whether or not there was some internal fuse that I've blown & what it would look like. And
again, I don't know where to attach the white common wire.

Any help would be greatly, greatly appreciated.

Thanks so much, in advance.

- Bill

[Virtual Repairman]

As long as your furnace has a 120 volt blower motor, there HAS to be a Neutral wire. I agree that you should use the Red wire (low speed) on the same terminal as the old one was. Don't use black unless you want a faster blower speed. +

There HAS to be a common line going to the old motor, or ir would not run. Better look more carefully at that schematic!

In a worst case scenario, I would hook up the white wire to ground and see if the motor runs with the other lead (red) connected to the fan relay as before. Tape up the other leads not used. There is a neutral wire going to the transformer on the furnace which can be used as the Neutral for the blower as well.
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[billnc]

I stayed up most of the night last night trying to research the 'net to figure out what to do.

I found many potential answers.

I decided to go with the simplest set-up first and see what would work.

The brown wires are both completely brown, no white stripe.

I retested the fuses, which I suspected I had blown in my first wiring attempt.
They were good when the repair guy was there, because the compressor was
running.

The fact that I miswired on my first attempt is why they say "Don't try this at home."
I prayed that I hadn't REALLY fried my complete system (and thankful that I hadn't
fried myself.)

I had, in fact, blown both fuses. I replaced them.

I connected the black high speed fan wire to the fan relay.

I screwed the green ground wire to the frame.

I connected the two brown wires to the capacitor.

Yes, I replaced the capacitor & yes, I made sure it was
rated for the motor.

There had been a blue wire attached to one of the posts
on the capacitor going off elsewhere into the system. I reattached
that blue wire.

I taped off the remaining speed wires.

I taped off and DID NOT connect the white wire to anything.

I inserted the power cutoff and heard the most beautiful hum in
the world. The motor was whirring away.

My guess is that the blue wire coming off of the capacitor is acting
as the common - return for the motor.

It has run fine since this afternoon.

I am really, really grateful, VRm, that you took the time to reply.

Thanks again.

- Bill