Lennox A/C masterboard bad? help with problems please!


Old 09-15-08, 06:57 AM
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Lennox A/C masterboard bad? help with problems please!


first, i'm not a handy man or have any knowledge with a/c units but a friend of mine, who is handy, has been helping me with a problem. We bought a house in December and have had a few problems with the York Diamond 80 unit. It is a 5 ton unit with gas heat and is outside. The previous owner said he replaced the master control board about two years ago and thats all he has ever done to the unit. the unit is about 4 yrs. old and the outside Trane compressor is about three years old. Here is what happened the last few times and how the problem was fixed.

the unit shut off during a storm where I suspected a little water leaking on the outside unit/air handler part. my friend replaced a fuse after trouble shooting and reset the switch on the control board and it was fine. Three other time in the next few months, the unit did the same thing after a storm were the power was lost and kicked back on. the unit was frozen up and after turning it off, letting it defrost, and sit for a while (about 30 min.), I reset the button and it came on.
This last time after a hurricane and power lost for 4 days, I returned home and the unit was frozen over after the elec. kicked on for about 30 minutes. By the way, I left the Unit on which was probably not the best thing...I know. So, I did all the things I did before but this time...nothing. I will say that the area near the coils, and the inside of the air handler/ control board area were wet due to the very, very high humidity. so, my friend came over again, checked the fuse and it was fine, tried to let it set and reset it but nothing. the compressor is fine and he unplugged some wire near where the gas part is inside the unit and the blower kicked on. It turned on even thought the unit was in off position on the thermostat. so, he tried to reset it but that light is still blinking red. He then put the unit on and it is cooling fine now except the red light is still on and cant be reset so it will blink green. The outside Trane is blowing hot air which i think is good??? I opened the unit this morning and there is no moisture in it but I don't know what to do. My friend said that I can let it run that way for a few days but will eventually need to tend to it as he is out of town for a week on business. He thinks the master control board might need to be replaced. The blower is blowing without kicking off but the outside compressor is kicking on and off so I don't know what to do. He said if it is the board, he can change it for me and save me some money. any thought??? sorry for the long post.

Ok... went outside and looked for info. to try to make this easier. We are just recovering from hurricane #2 and we really don't want to spend more $ than we have to!

Outside furnace/air handler unit thing says on the door: York Diamond 80

Model: P4HUC20N09201A
SN: WKKM038280

The control board says Source 1 and I think the letters are D's and not o's or zeros??

bar code on the board says: 18393 and the other numbers on the board are:

D31-D1972-000 (hard to tell if they are D, o or zeros!)

and under that it says:

6DT-1 CL-A5



Last edited by bj102598; 09-15-08 at 07:52 AM. Reason: sorry. this is not a lennox unit... I don't think!
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Old 09-16-08, 07:45 AM
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Join Date: Jun 2008
Location: Rocky Hill, CT. USA
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You can fix this two ways. You can have your friend throw parts at it until it runs correctly, or you can get a Lennox tech. with the right diagnostic tool. A new board can run close to
$800-1000. A proper service call to diagnose - under $100.
Lack of stress and grief? Priceless...
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