HH18HA504 – LIMIT SWITCH (L220, AUTO, LARGE BASE)

Automatic-reset limit switch for Carrier, Bryant and Payne furnaces, recorded as a large-base switch with an L220 degree F opening point. It interrupts the control circuit on over-temperature and re-closes by itself once the sensed temperature drops back into range. Confirm the base style and L-number against the switch being replaced. Carrier 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

The 310, 311 and 312 series are the Bryant, Payne and Day & Night versions of the same chassis. CRITICAL: the neighbouring HH18HA numbers differ only by temperature and are NOT interchangeable — HH18HA496 is 200F, HH18HA497 is 190F, HH18HA498 is 210F, HH18HA499 is 165F, HH18HA502 is 180F, HH18HA505 is 235F, HH18HA506 is 240F, HH18HA507 is 185F, HH18HA508 is 160F, HH18HA509 is 195F. Published application data. Always match the full model and serial number on your unit before ordering.

Specs

• Part NumberHH18HA504
• Brand (as recorded)Carrier
• Product TypeFurnace limit switch
• Reset TypeAutomatic
• Base StyleLarge base
• Limit SettingL220 degrees F
• Data SourceOTP stock record - not manufacturer-verified

Fits these models

• 58STX045 series (10008, 10108, 11108, 12108, 13108, 14108, 15108, 16108, E10108)
• 58STA045 series (10008, 10108, 11108, 12108, 13108, 14108, 15108, 16108, E10108)
• 58DLA045 series (10008, 10108, 11108, 12108, 13108, 14108, 15108, E10108)
• 58DLX045 series (10008, 10108, 11108, 12108, 13108, 14108, 15108)
• 58CTA045 series (10108, 11108, 12108, 13108, 14108)
• 58CTX045 series (10108, 11108, 12108, 13108, 14108)
• 310AAV024045 and 310JAV024045 (AA, AB, AC, AD, AE, AF, AG, EA – JA)
• 311AAV024045 and 311JAV024045 (AA, AB, AC, AD, AE, AF – JA)
• 312AAV024045 and 312JAV024045 (AA, AB, AC, AD, AE – JA)

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.