Troubleshooting the gas furnace with ICM 281 board

Old 02-05-16, 09:16 PM
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Troubleshooting the gas furnace with ICM 281 board

It is about the board ICM 281 and its error codes in particular code 12 and code 31. I guess many of you have a lot of frustration trying to troubleshoot their heater problem using this board. It is because of the lack of support and very disappointing description of error codes.
When I installed the new board, I thought it will solve my problem with old board, but I immediately received the error. In frustration I repeated the run several times but now I recognized the error code 12. I realized later the fact that I missed the first error on the first run gave me many hours of torture. The error code 12 explanation is “Blower on after power up and then blower runs for 90 seconds unit is powered up during a call for heat”. It is a very vague explanation. I rushed to the net and found troubleshooting guide for another furnace but it has more than 50 steps. I was shocked. Fortunately I noticed that inducer motor does not run, but I remembered that it did run. So I turned the thermostat off and initiated self test. To my surprise it ran good. The inducer motor started, then the igniter heated up, and finally main blower run. I turn the thermostat on and now discovered the error code 31. When I repeated the run turning thermostat off and on the board shown error code 12 ! ATTENTION !! My conclusion is: the error code 12 indicates that previous run was with error, and self test simply clear the error code from the board memory. So I realized that now would struggle with error code 31. Instruction for the code 31 says “Pressure, draft safeguard, auxiliary limit ( when used ), blocked vent shut off (when used), switch did not close or reopened”. B******* ! I will tell you later what does error code 31 means.
I started my exercises with the cycles: on thermostat, run, thermostat off, self test, and thermostat on. Now the inducer motor runs on the first run after self test. I checked the pressure switch, it is easy, disconnect one terminal and measure with a meter resistance across the terminals. I found that the switch is closed, which confirms that it works fine. There were another devices on this circuit. First I thought there are also pressure switches (sorry I am NOT professional) then I found that they are over temperature switches and they should be normally closed. I check these with no power, and found they are open. Those switches, with over temperature are tripped to the open state, and stay at the same open position. They have a special button on each of them, which, when pressed reset the switch. I did and tortoise starts working. I understood now that code 31 means there is a problem on the circuit between pin 11
on the edge connector (yellow wire) and pin number 6 (orange wire).
Happy troubleshooting.
Old 02-05-16, 11:22 PM
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Welcome to the forums.

Didn't really see a question here and a bit difficult to follow your troubleshooting methods but I see an issue.

A limit switch that you need to push a red button on it to reset it is usually a rollout switch and is a sign of a burner, heat exchanger or flue problem.
Old 02-06-16, 03:24 PM
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Take the cover off the burner compartment of the furnace.

Carefully observe the sequence of events that occurs when you turn up the thermostat. Post that sequence here in order and in detail.

An excellent method of diagnosing furnace problems is to understand that a furnace doesn't just turn on. It has to complete a sequence of events in order to produce heat.

If you understand how far the furnace is in that sequence before it stops, that tends to point to particular problems.

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