Description:

Genuine GM‑spec thermal limiter for vehicles equipped with the Frigidaire A6 compressor. Protects the compressor clutch circuit from overheating.

Covers GM A6 compressor systems, 1961–1986

Core rule: If the vehicle used a Frigidaire A6 compressor, it used a thermal limiter in the clutch circuit. GM changed limiter part numbers over time, but the function and fitment remained consistent.

🚗 GM Passenger Cars — Model‑Year Coverage

Chevrolet

• 1961–1986 — Impala, Caprice, Bel Air, Biscayne

• 1964–1983 — Chevelle, Malibu, Monte Carlo

• 1962–1979 — Nova

• 1967–1981 — Camaro

• 1970–1988 — Chevette, Citation, Celebrity (A6 used in early years only)

Pontiac

• 1961–1986 — Catalina, Bonneville, Grand Prix

• 1967–1981 — Firebird

• 1964–1987 — LeMans, Tempest, Grand Am

Buick

• 1961–1986 — Electra, LeSabre, Riviera

• 1964–1987 — Skylark, Regal

Oldsmobile

• 1961–1986 — Delta 88, 98, Toronado

• 1964–1987 — Cutlass, Supreme, Calais

Cadillac

• 1961–1986 — DeVille, Fleetwood, Eldorado, Seville Cadillac used the A6 longer than any other GM division.

🚚 GM Trucks — Model‑Year Coverage

Chevrolet Trucks

• 1963–1986 — C/K series

• 1967–1986 — Suburban

• 1969–1986 — Blazer

• 1975–1986 — G‑series vans

GMC Trucks

• 1963–1986 — Sierra, Jimmy

• 1967–1986 — Suburban (GMC)

• 1975–1986 — Vandura

Medium‑Duty GM

• 1965–1986 — School bus chassis, commercial trucks A6 compressors were extremely common in fleet vehicles.

Thermal Limiter Part Number Compatibility

Here’s the breakdown of which limiter numbers match which eras.

🔧 6551238 — Early/Mid 1970s

Used on:

• 1971–1976 GM passenger cars

• 1973–1977 GM trucks

• All A6‑equipped Cadillac 1971–1976

This is one of the most common mid‑70s limiter assemblies.

🔧 6551258 / 6551259 — Late 1970s

Used on:

• 1976–1980 GM passenger cars

• 1977–1981 GM trucks

• Cadillac 1976–1980

6551258 = boxed assembly 6551259 = limiter unit itself

🔧 6556440 — Early 1980s

Used on:

• 1980–1986 GM passenger cars

• 1981–1986 GM trucks

• Cadillac 1980–1986

This is the Bussmann THL replacement you uploaded earlier.

GM Division‑by‑Division Summary

Chevrolet

• 1961–1970 — Early limiter variants

• 1971–1976 — 6551238

• 1976–1980 — 6551258/6551259

• 1980–1986 — 6556440

Pontiac / Buick / Oldsmobile

Same timeline as Chevrolet.

Cadillac

Cadillac used A6 compressors longer:

• 1961–1976 — Early + 6551238

• 1976–1980 — 6551258/6551259

• 1980–1986 — 6556440

GM Trucks

• 1963–1977 — Early + 6551238

• 1977–1981 — 6551258/6551259

• 1981–1986 — 6556440

Features: • GM part #6551238 • Patented limiter assembly (HX16 / 5VA433A2) • Fits 1960s–1980s GM cars & trucks • NOS condition with original box