Relay switch on a furnace control board


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Old 02-11-13, 06:35 PM
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Unhappy Relay switch on a furnace control board

I have an eight (8) year old Carrier gaspack furnace unit whose control board has apparently died although it worked with the fan in the "on" position. I found an exact replacement but it did NOT fix the problem at all, i.e., having the fan turned on when signaled by the flame sensor (fan in the "auto" position). The repair guys tell me that the relay switch was and is again the likely culprit and I must have (coincidentally) a defective board from the manufacturer. My question is: can this be the case or did I damage it or did the unit damage it by shorting it somehow (did it do this to the original board)? The furnace works if the fan is in the "on" position (where the fan is ALWAYS blowing). I just got the replacement, but am afraid to install it for fear that it will NOT work again. Can someone PLEASE tell me what I must do? If you need any other information, please contact me.
 
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Old 02-11-13, 07:06 PM
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Post the model number so we can see the diagram.
 
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Old 02-12-13, 03:59 PM
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I forgot to post the model & serial numbers. The model number for this high efficiency carrier unit is: 48XP-036090301; the serial number is 3204G31149. I would like to do the work this weekend, but I will wait until I hear back from you folks. Thanks!
 
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Old 02-12-13, 04:08 PM
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Thanks, Houston204. I posted the model & serial numbers. I appreciate your help very much. Thank you!
 
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Old 02-12-13, 06:29 PM
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http://www.docs.hvacpartners.com/idc...t/48xp-3si.pdf


What is A (violet) plugged into on the fan control board?
 
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Old 02-12-13, 07:07 PM
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I have no idea...may I ask the basis for the question?
 
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Old 02-12-13, 08:11 PM
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The gas heat cfm selection (violet) should be set at 90 over 1250.
Depending on the model, there may be a Not Available pin...




Do you have a meter?
We should get 24VAC between motor harness terminals 1 and 13 with a stage 1 heating demand (on the 16 pin connecter to the motor).

 
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Old 02-13-13, 04:27 AM
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Okay, I will check to see if A (violet) is either plugged into 90/1250 or if there is a Not Available pin. If it is plugged into 90/1250, do I still check for the VAC between motor harness terminals 1 & 13? Where do I look for those terminals? Is that a third board in the heating unit? Does the unit need to be heating when I check them? Thanks, again!
 
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Old 02-24-13, 02:32 PM
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I found that A (violet) is indeed plugged into 90/1250. I just changed the control board yet again. Please tell me what else there is to do...please...thanks!
 
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Old 02-24-13, 05:16 PM
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I think you have a blower motor problem... Houston, do you know if this is an X-13 motor or a true VS motor?
 
 

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