Gas and Oil Home Heating Furnaces - Primary Unit Limit Open???

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dakine
01-27-06, 07:58 AM
My cental heating unit, (propane), will not kick on. It sounds like it is about to, but the fans will not kick on. I checked the unit, it was still humming, even with the heater in the off postion, and where the humming is coming from is a flashing light with flashing error codes. Mine was flashing twice....which says it is the 'primary unit limit open'. What does that mean?? and can I fix that myself???
Thank you.

Jay11J
01-27-06, 08:32 AM
Have you tried shutting it down, and reset it?

If the limit has tripped, could be a few things wrong.

-Poor/no air flow
-dirty filter
-plugged coil
-return vents plug/blocked
-too many vents closed
-oversized furnace
-overfired burner.
-blower motor not working.
bolide
01-27-06, 09:21 AM
where the humming is coming from is a flashing light with flashing error codes.
Hum could be a relay or the transformer. Transformer hum is not unusual.


Push the reset button on the limit switch.