STC4228 – TEMPERATURE FUSE LINK (L235°, 15A)

A one-time thermal fuse link that opens (blows) at 228°F to protect HVAC equipment from overheating. If your furnace or heater has shut down and you find a blown fuse link, replace it with the correct temperature rating. Also investigate what caused the overheat — a clogged filter, failed blower motor, or blocked ductwork are common causes.

Specs: 15A, opens at 228°F (109°C), one-time-use thermal cutout

Replaces: NTC227, STC4228

Fits: Furnaces, electric heaters, and HVAC equipment using a 228°F thermal fuse link for overheat protection

In stock at Open To Public HVAC Parts in Dallas. We test parts at the counter before you buy. Call or text (214) 340-9421.

Specs

• TypeTemperature fuse link (one-time)
• Trip Temperature235°F
• Amp Rating15 A
• Type BehaviorOne-time use (replace after trip)
• OEM CompatibilityUniversal

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• NTC227
• STC4228

Not sure if your number matches? Call (214) 340-9421 or bring the old part in — bench-testing is free.

Fits these models

• Universal temperature fuse link with 15A pass-through rating — safety cutoff for electric heat strips and gas furnace plenums
• Match the L-rating (trip temp) and amp rating to your existing link
• Common applications: most residential air handlers with electric heat strips (Rheem, Goodman, Trane, Carrier, York, Lennox, First Co)

What does L333° mean on a temp fuse link?

The L-rating is the trip temperature in Fahrenheit. L333° trips at 333°F. Common ratings: L235°, L257°, L300°, L333°, L377°, L438°, L468°. Match your unit's data plate exactly — these are not interchangeable.

Why does my temp fuse link keep blowing?

On electric heat strips: usually restricted airflow — clogged filter, dirty blower wheel, undersized return, closed-off supplies. The strips overheat without enough air moving across them. On gas furnaces: usually flame impingement from a cracked heat exchanger, misaligned burners, or wrong manifold pressure. Fix the root cause; don't just keep swapping links.

One-time vs resettable — which do I need?

Look at what your existing link is. One-time ceramic / non-ceramic links are SAFETY devices designed to fail permanently — they're catastrophic-failure protection. Resettable breakers are convenience devices for short-cycling. They're NOT interchangeable; match what your equipment was designed for.

Can I bypass the fuse link with a jumper wire?

No. The fuse link is a safety device — bypassing it can cause fires, melted ductwork, CO production from incomplete combustion, or worse. If yours is blown, replace it. Period.

How do I tell if the fuse link is blown?

Use a multimeter on continuity / resistance mode. A healthy link reads near 0 ohms (closed circuit). A blown link reads infinite / OL (open circuit). Visual inspection helps too — blown links often have a visible gap or melted appearance.