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Diagnostic code: Red-Slow Flash, On. Indicates limit switch…

Customer Question
Diagnostic code: Red-Slow Flash...

Diagnostic code: Red-Slow Flash, Green On. Indicates limit switch open. How do I reset the limit switch?

Contractor's Assistant: I'll do all I can to help. How long have you been dealing with this?

It stopped working in the middle of the night.

Contractor's Assistant: Do you plan on doing the work yourself?

Yes

Contractor's Assistant: Anything else we should know to help you best?

I have followed the procedure for restarting, but no luck

Submitted: 6 months ago.Category: HVAC
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Answered in 1 minute by:
12/28/2017
HVAC Technician: Rick, HVAC Supervisor replied 6 months ago
Rick
Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 24,414
Experience: 40+ yrs. experience as a licensed oil & gas technician.
Verified

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your

issue. First I’ll need some more info so I have a more complete picture of your situation. What is the brand and model of your furnace?

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Customer reply replied 6 months ago
Lennox G43UF
Customer reply replied 6 months ago
I don't want a phone call. Are you there?
HVAC Technician: Rick, HVAC Supervisor replied 6 months ago

Call prompt is automatic I have no control over it. We can continue here

Have a little patience, I'm not a machine and it takes a while to research your model.

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HVAC Technician: Rick, HVAC Supervisor replied 6 months ago

You can't reset the limit. If it's working properly it will reset itself once it cools down. Do you know where it is? do you have a multi-meter?

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HVAC Technician: Rick, HVAC Supervisor replied 6 months ago

When was the last time the filter was changed? There is a primary on the front and possibly a secondary on the blower housing. Do you have continuity across the main limit and where the limit circuit leads connect to the board?

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Customer reply replied 6 months ago
The filter was dirty. I'll have to find the leads.
HVAC Technician: Rick, HVAC Supervisor replied 6 months ago

Ok, dirty filters can mean poor air flow and an overheating heat exchanger which trips the limit but it should reset on its own after it cools down. If the limit is still open it will have to be replaced.

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Customer reply replied 6 months ago
OK. I'll check it out. Thanks
HVAC Technician: Rick, HVAC Supervisor replied 6 months ago

You're welcome

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