Trane Voy Comb Motor

[mrhvacmechanic]

Sorry to bring this up again!
Looking at voyager print there are four wires to Fasco comb motor, red-purple-orange and black. 208v motor

The fasco print on motor shows High speed:
pur line
bk line
or ins
red ins

Low speed:
pur line
org and blk together
red line

Since I don't know how to download unit print to this site, can someone explain how the combustion board switches speed on this motor during purge, low and high fires???????
Looking at the unit print and the way wires are connected to the board which switches speeds it can't do it the way it showes on print??Please explain what I'm missing on this??Voltage is always present to motor on red and purple?Even though its not rotating, is there somthing in motor that effects this operation?

[john77420]

the control board runs the comb motor according to the staging of heat. there is always power at the motor on all voyager units, that is how trane has always done it, not exactlly sure why. usually the comb motor comes on to purge, fires, runs, and than goes to high speed according to staging.

[too tall terry]

the control board runs the comb motor according to the staging of heat. there is always power at the motor on all voyager units, that is how trane has always done it, not exactlly sure why. usually the comb motor comes on to purge, fires, runs, and than goes to high speed according to staging.bingo!!!!!

[maxster]

here is the print out of the IOM hope it is clear from the sizedownhttp://img346.imageshack.us/img346/7426/tranecbmzx4.jpg

[mrhvacmechanic]

Why doesn't motor rotate with 208v applied to it?

[mrhvacmechanic]

If black and purple is powered all the time why doesn't motor rotate. I am familiar with high and low fire operation.
Trane print doesn't match motor diagram, somthing is missing???

max, you print doesnt show third set of contacts on black wire?The relay when it switches would apply power to red purple and black lead when it switches

[jayguy]

Sorry to bring this up again!
Looking at voyager print there are four wires to Fasco comb motor, red-purple-orange and black. 208v motor

The fasco print on motor shows High speed:
pur line
bk line
or ins
red ins

Low speed:
pur line
org and blk together
red line

Since I don't know how to download unit print to this site, can someone explain how the combustion board switches speed on this motor during purge, low and high fires???????
Looking at the unit print and the way wires are connected to the board which switches speeds it can't do it the way it showes on print??Please explain what I'm missing on this??Voltage is always present to motor on red and purple?Even though its not rotating, is there somthing in motor that effects this operation?

the fasco diagram and the voyager diagram are the same: on low speed, the org and blk are tied together and pur and red are line. on hi speed the only difference is that fasco shows red is insulated when trane has power to it, but since it is at the same power and phase as black, it is basically the same.

think of the motor as 1 winding (like the primary side of the transformer but with four taps). purple is H1, org is H2, blk is H3, red is H4 (pretend the transformer/motor keeps going on the wiring diagram). power is applied to purple energizes windings between H1(pur) and H2(org), shorts around windings H2(org) and H3(blk) and energizes windings H3(blk) and H4(red) and leaves out H4(red).

on high speed, power enters H1(pur), energizes windings H1(pur) and H2(org) and H3(blk) and leaves on H3(blk). since H3(blk) and H4(red) are at the same power level and phase, windings H3(blk) and H4(red) have no current flow.

power should not be at the motor "at all times". if you look at the print, on the left side of the transformer is relay H, it is energized with a call for heat, that in turn energizes the transformer which powers up the motor.

this looks/sounds real good in my head...hope it is not too fuzzy for you.

[ReverseRotation]

It was mentioned that orange and black are actually shorted for low speed, via the ing board. on the wiring diagram it has what appears to be one relay with a com, n.o, and n.c contacts (one coil). However i think I am viewing this wrong. is there 2 relays? Please see the attachment.

[ascj]

It was mentioned that orange and black are actually shorted for low speed, via the ing board. on the wiring diagram it has what appears to be one relay with a com, n.o, and n.c contacts (one coil). However i think I am viewing this wrong. is there 2 relays? Please see the attachment.

Yes there is two relays. First relay closes Com, for low speed. Second relay closes NO(high) and opens NC(low).

The easiest way I explain it to people is: There are two sets of winds. One between Red and Orange and one set between Black and Purple. With no call for inducer you have power to Red and Black, but you wont get anything happening because Orange and Black are the other ends of those winding and the windings are then open. For LOW speed the board close a contact to connect Black and Orange. Now you have closed both sets of winding and inducer runs low. Now for High speed, the second relays closes Red to Black, but opens up Orange. Now you have a complete circuit between Orange and Black's winding but since Orange is open the other set of winding is open. Now the inducer with run twice as fast(high speed) since you using less winding.

Hope that helps.