# code 33 furnace error



## yuri (Nov 29, 2008)

If it is a Carrier/Bryant/Payne code 33 is open limit. means that not enough air is moving thru the furnace and it is cycling on the limit control. dirty ac coil, filters,ducts, vents closed could be the problem.


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## mijakb (Nov 21, 2011)

checked those things, but all seem to be fine. Heres one more piece that we just figured out. It only happens when the downstairs calls for heat, not upstairs. Thermostat was already replace downstairs, as we thought that was the original problem, but still continues.


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## yuri (Nov 29, 2008)

I assume you have 2 furnaces? Yes?

Remove the tstat from the problem one and pack pink fibreglass insulation in the hole behind it in the wall. You may be getting a draft thru there and aggravating the tstat.

code 33 is temp related so it has to be a problem with airflow. if they share the same return air duct then one may be overpowering the other.


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## mijakb (Nov 21, 2011)

Hi Yuri.
No, we have one furnace with 2 zones. Is there a door?? for zone 1 and for zone 2?


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## yuri (Nov 29, 2008)

I would literally have to see your setup. In some cases they have a "barometric damper" bypass pipe from the supply plenum so the excess air that gets blocked when 1 zone/damper closes can bypass back into the return duct. if that is out of whack/sticking or not set properly that may be why it is overheating.


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## mijakb (Nov 21, 2011)

Okay. Thanks Yuri. We'll have to contact someone here to help with that. I appreciate your response. I'll post the outcome.


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## yuri (Nov 29, 2008)

Good Luck.

Make sure you ask them if they have worked on zoned systems as they are rare and most guys don't see them or know them well. Talk to the service manager and explain what you have.


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