York Diamond 80 intermittent code 4


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Old 01-15-23, 04:36 PM
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York Diamond 80 intermittent code 4

My home has a York Diamond 80 furnace and has a history of intermittent no heat or blowing cold air for sometime. It flashes code 4 most of the time when it fails. But it also has symptom of flames goes out after ignition. So I have replaced new frame sensor, high limit switch and pressure switch and the code is still coming once every few heating call. HVAC technician is called and was not able to discover the issue. I finally found the problem seems around the big white connector to the control board at the top right corner.

When I wiggle the wires or the connector, the flame and furnace may shut off. If heating is called by thermostat and the furnace has no action and no code. Wiggle wire bundle or the connector will trigger the furnace to start its heating process. The control board is attach to a base that attached to the blower and small vibration can be felt. So the issue may be related to the connector or something near the connector on the control board.

I have tried to clean the female and the male pins to make sure they have good contact. But the problems persisted. My problem is that I do not know if the bad contact is in the connector or on the control board. Does anyone experience similar issue and how do you fix it?

By the way, the furnace can shut off in the middle of blowing warm air without any code. If wiggle the connector or wires bundle it will start the ignition process and produce heat again.
 

Last edited by msun101; 01-15-23 at 05:28 PM.
  #2  
Old 01-15-23, 08:53 PM
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Yes.... that 12 pin plug can get corroded. Unplug it. Spray it with a small amount of contact cleaner and reconnect it to the board several times. If you don't notice a difference... in other words you still have an intermittent problem when moving that connector.... more than likely you have broken solder on one or more of the pins where soldered to the board. That would indicate the control may need to be replaced.
 
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Old 01-16-23, 09:40 AM
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Thanks PJmax. You are right on. I found one suspected bad solder point on one pin. Resoldering it seems help. The furnace has consistently fired up more than 5 times. I Should be able to tell if it is finally fixed in a few days.
 
 

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