[garryshaf]

Recently bought a replacement control board for my 14 year old York furnance. The replacement part number is 21-33102956000. I am getting a repeating "nine red blinks" on the LED error indicator. Tha means polarity or grounding problem. My old board grounded through a screw that connected the board to the sheet metal brace. The hole in the old board had a metal tab (labeled on board as ground) in the screw hole...establishing the ground. I don't see a similar grounding mechanism for my new board. I never had the grounding error code before...so I am assuming it is something to do with the new board. Any ideas? Thanks. Garry

 

[beenthere]

Make sure that the transformer connections to the board aren't reversed.

You can also run a wire from the boards common to the chassi(be carefull that polarity is correct first, or you can smoke the new board).

 

[yuri]

I had the EXACT same problem. Change the (2) 24 volt wires from the transformer around on the new board, reverse them. ie: switch R and C around.

 

[garryshaf]

Terminology

When you say "common" ... I take it that can mean connect ground wire from a "neutral" lead to the chassi. There is another empty lead called "park" ... Thanks. Garry

 

[yuri]

Carefully look at the the power transformer. The primary side is usually black and white (PRI) and 120 volts. The secondary side (SEC) is blue or yellow and 24 volts and attaches to the board as SEC. Switch the 2 secondary wires positions (one for the other) on the board. The old board was not polarity sensitive, all new ones are.

 

[beenthere]

When you say "common" ... I take it that can mean connect ground wire from a "neutral" lead to the chassi. There is another empty lead called "park" ... Thanks. Garry

No.

Common is from the transformer secondary side.
One terminal is Marked R or +, the other is marked C or -, the C/- is common.

A neutral is never a common.


park terminal to put unused blower motor wires, so they aren't hanging in mid air, or shorting out against something else.

 

[garryshaf]

Fixed! Thanks.

Beenthere, Yuri. I switched the two secondary wires from the transformer around on the board and furnance is now working. THANKS! Garry

 

[yuri]

No Problema. Pay it Forward and Help someone else.:thumbsup:

 

[beenthere]

Beenthere, Yuri. I switched the two secondary wires from the transformer around on the board and furnance is now working. THANKS! Garry

Congrats.

Its a fairly common thing when going from 1 style board to another.

 

[yuri]

I didn't know that until a month ago. Was 2 steps away from calling the new board bad and getting another one and egg on my face. I don't see too much York where I am.

 

[beenthere]

I didn't know that until a month ago. Was 2 steps away from calling the new board bad and getting another one and egg on my face. I don't see too much York where I am.

I'd almost swear the change the polarity of the boards every so often just to screw us up in the field. :furious:

But I can't prove it.

 

[yuri]

Now we have a conspiracy on our hands. Oy. Freedom 55 is lookin good now.:laughing: