B1370905S – HIGH LIMIT SWITCH (3″, L290°)

High-temperature limit switch for Goodman/Amana furnaces, recorded as a 3 inch style with an L290 degree F opening point. It interrupts the control circuit on an over-temperature condition, typically caused by restricted airflow, a dirty filter or a failed blower. Match both the physical style and the L-number when replacing. Goodman/Daikin publishes no public part detail, so the specifications below come from our own stock records; confirm against the part nameplate before installing.

Specifications from our own stock records. The manufacturer does not publish a public page for this item.

Before you order

B1370905S is discontinued and superseded by 1370905S — same L290-30F control, current number. Note that GMP100-4 uses BOTH this L290 limit and the B1370155 auxiliary limit; they are two different switches in the same furnace. Published application data. Always match the full model and serial number on your unit before ordering.

Specs

• Part NumberB1370905S
• Brand (as recorded)Goodman
• Product TypeHigh limit switch
• Style3 inch
• Limit SettingL290 degrees F
• FunctionOpens control circuit on over-temperature
• Data SourceOTP stock record - not manufacturer-verified

Fits these models

• GCC090B40A
• GCC090B40B
• GCC090B50A
• GCC090B50B
• GCC090C40C
• GCC090C50C
• GCC115B50A
• GCC115B50B
• GCC115C50C
• GCN90A40
• GCN115A40
• GHN90A35
• GHN90A50
• GHN115A50
• GMP100-3
• GMP100-4

What does L200-40 mean on a furnace limit switch?

L is limit, 200 is the temperature in F where the contacts open on a rise, and 40 is the differential, so it closes back around 160F. That is an auto-reset disc. Manual-reset limits have a button and stay open until somebody pushes it. Bring the old one in so we can match the temperature, the mounting hole pattern, and the probe length together.

My limit keeps tripping. Is the switch bad?

Usually not. A limit is a safety reading real heat, and most repeat trips we hear about trace back to airflow - a loaded filter, closed or blocked registers, an undersized return, a dirty blower wheel, or a plugged evaporator coil sitting above the heat exchanger. Check temperature rise against the nameplate range, often 40-70F or 45-75F. Rise above the top number means airflow, not a bad switch.

Can I use a hotter limit if that is what is in stock?

No. L200, L230, L250 and L290 differ only by trip temperature and by base or probe size, and they are not interchangeable. Dropping a hotter limit into a furnace that specced a cooler one lets the heat exchanger run past the temperature it was tested to. That is defeating the safety, not fixing it.

Does insertion length matter?

Yes. A 3 inch probe where 5 inch was called for sits in the wrong part of the airstream, reads low, and trips late or never. Measure the old probe from the back of the mounting plate to the tip.