Blower Motor Not Working Intermittently

5 years ago

Hello All,

I've been struggling with this for a few days and I'm hoping someone here may have some ideas on what's causing my issue.

About 2 weeks ago the furnace (Carrier) started having issues. Typically it happens at night, but the heat will just stop working and the furnace gives me the error code 13 or 33 (limit switch) depending on the day. Its been difficult to diagnose since it only happens intermittently, but the 1 time I happened to see it fail in action, this is what happened...

The furnace got the call for heat, the exhaust fan started running (the one that goes to the roof), the flames kicked on and seemed to be normal. However, the blower never kicked in and after about a minute the unit shuts down and gives the error code 13. Usually when this happens I can the power off and on and it will start working again, but sometimes no matter what I try it jus comes back on with the same code (33 in this case). I assume when this happens that the 3 hour lockout was triggered. I assume that something is causing the blower to not come on, which is letting the flames overheat the unit and tripping the limit switch, but i'm not 100% sure.

The blower doesn't seem to have any issues turning on for cooling on fan mode. It only happens with heat, and only sometimes. There's no noticeable issues with the blower when it's running as far as I can tell. Also, this system is 6 years old and this is the first time this issue has occurred. I switched 1 nest thermostat for a newer model within the last year, but nothing else has been changed with the system.

More info about my system:

- 3 zones (1 per floor) with 1 air handler/furnace and 1 fan coil unit. The zones are controlled with dampers that are controlled by a board HZ311.

- The furnace control board is (cepl130934-01)

- The blower motor is (KMSAH012C03)

We bought a couple of space heaters to keep our bedrooms reasonable at night, but I would love to get this fixed. I hesitate to pa a technician to come out because the issue doesn't happen consistently. And generally, I'd prefer to fix these things myself unless it's just way out of my comfort zones. Any help would be greatly appreciated!

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Comments (4)

mike_home
5 years ago
Error code 13 for Carrier is a limit circuit lockout. That usually is due to a lack of air flow. Is the filter clean and properly positioned? Also check nothing is blocking the flue exhaust. There is a chance the limit switch itself is malfunctioning. In that case it would need to be replaced.

If you provide the error codes and a description of what is happening, a good tech should be able to figure out the problem if you are not able to resolve it yourself.
Cameron Christian
Original Author
5 years ago
The filter is clean/new.

Is there a possibility that its too high of a MERV or something and air flow is being overly restricted? its only Merv 11.
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fsq4cw
5 years ago
last modified: 5 years ago
As this is a fossil fuel burning system, probably gas, I would recommend having it properly repaired by a professional and not have yourself or your family exposed to any risk of carbon monoxide, fire, explosion or anything else.

We always hear about these types of tragedies at this time of year - Why risk being a statistic.

IMPO

SR
mike_home
5 years ago
last modified: 5 years ago
It is possible the filter is too restrictive, but likely not the problem if you have used the same filter in the past. Have you recently closed any of the supply vents? Are the dampers to the zones operating properly? When was the last time furnace has a preventative maintenance check?

The furnace is shutting down due to a safety issue. You need to have this have a professional determine the cause and the fix. Since it is only 6 years old you may be covered by the parts warranty. Call the company who did the installation if you feel they are competent.