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new member

1 post(s)
posted on 10/6/2007

I have a York Diamond 80 with a White Rodgers 50A50-241 controler. A few days ago I noticed the fan would continue to run after the A/C unit shut down. I had to shut the power off to the unit. The next time it ran, same thing. I switched to heat and the same problem. After the burner shut down the fan continued to run for 20 minutes. The only way to stop it is to shut the power off. Today I found that it runs even with both the thermostat heat/off/cool switch in the off position and the fan switch in the off position. I have to shut the power off to shut the fan down. When the unit is running, the diagnostic indicator light is flashing continously. According to the label on the controler, that means "Flame - No call for heat". What do I check next?

Thanks, Bruce     

Replies [ post reply ]

senior member

31 post(s)
replied on 10/8/2007

It means the controller is detecting a flame. if the burners are not on you will have to call a tec. to trouble shoot. if you have put the thermostat to off you have disconnected 24v back to the furnace. if you do have a flame (and I don't think you do- because you have not say you are too warm) look for a short in the R and w wire back to the furnace.



junior member

10 post(s)
replied on 10/8/2007

W on the thermostat is the heat wire. Disconnect that and see if it continues.


new member

1 post(s)
replied on 10/11/2007

Disconnected the wire from the W terminal of the thermostat, and fan stopped. Looks like it is the thermostat. I will change it tomorrow.



new member

1 post(s)
replied on 1/10/2010

I have this same problem.  Replacing the thermostat did not fix the problem.  

Also, there is an audible click (like a tripped fuse), in the control board area, a second or two from plugging in the unit, when the LED light starts blinking and the blower turns on to stay on.

I get ~26 volts at the W wire at the control board during a call for heat and 0 with no call for heat.  R has ~26 volts always.  These are correct if I understand right?

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