Nordyne FT3BA060KA - Contactor Problem?

[seanmwalls]

Hello,

I have a Nordyne FT3BA060KA which does not start when the thermostat calls for cold. I believe it may be either the contactor or the control board. Based on other posts, I measured voltage at each of the wires that attach to the coil. When 1 lead is on the terminal and 1 on the ground, I get 22 VAC for each line. When I take the voltage across the leads when the thermostat calls for cold, I get 0 volts. When I manually press the contactor bar, everything starts up like normal and cold is delivered to the house. The main leads coming off the contactor each have 120 VAC to ground and 240 VAC across. I am hoping I can write this off as a contactor problem. The fact that I don't have a coil lead that is 0 VAC to ground has me perplexed. Could this indicate a short in the coil? Any suggestions would be greatly appreciated!

Thank you in advance,
Sean

[Robert]

Hi Sean,

Remove the two coil wires one at a time and test the end to a good ground for 24VAC WITH a call for cooling from t-stat.

Set t-stat to call, remove one at a time with needle nose pliers with electrically insulated handles.


Get a hold of wire insulation and test the end with one meter lead and the other lead to ground.


You should read 24VAC on ONE wire only and 0VAC on the other.

The one with 0VAC needs checked from that point all the way to the transformer for a loose connection or break in wire.


IF you have some wire, leave that wire disconnected at contactor coil, reconnect other wire.


Then take new wire and connect at contactor coil in place of current wire.


Loosely run it to transformer common side and connect where current wire was.


Then set t-stat to call and see if all is ok.


Sounds like you may have lost your common or neutral to the coil.


Will be away all day tomorrow, but will check back when I get in office tomorrow evening.


Thanks,
Robert

[seanmwalls]

Thanks for the info.

When I measure each seperately, I get 1 lead with a 24 VAC reading and the other has a 13 VAC reading. Neither of the leads is 0 VAC. Each of these wires connects right into the control board.

I measured the voltage at the transformer (inside the house in the blower housing) and I get 0 VAC on the common, 24 VAC on the 24 output, and 120VAC on both of the inputs, so I think everything is fine there. That leads me to belive that the problem is either the board or the line between the tranformer and the board. Thoughts?

Thanks again,
Sean

[Robert]

Hi Sean,

Was away from office all day and just getting this. I don't have your wiring diagram in front of me at the moment, what designation does each of the two wires connect to on the board ?


Test across those two board connections and then each to ground at the board connections.



Thanks,
Robert

[seanmwalls]

The wire coming out of T1 appears to have been the problem. I have removed it and patched over to the common and things are running normally again. Now it looks like I'll need to find a replacement board before winter hits! Thanks for your help.

[Robert]

Hi,

I will send control board ordering info in a day or two in case you're interested.



Thanks,
Robert

[seanmwalls]

That would be greatly appreciated! Thank you again for your help!

[Robert]

Hi,

Defrost Control Board # 917178A can be seen and ordered from here by scrolling down:

http://www.aberdeenhomerepair.com/store ... ESC&rpp=25



Thanks,
Robert