Do car ac compressor replacement problems track days at 90°F or more across states?

Across U.S. states, NHTSA owner complaints about car ac compressor replacement run higher where very hot days are higher, after adjusting for the makes sold in each state. This is an association across states, not proof that very hot days causes this repair.

How to read it: Each dot is a state. Further right means more days at 90°f or more; higher up means more complaints for this repair than expected (1.0 is average). If the dots climb to the right, reports of this repair rise with days at 90°f or more.

What it shows: States with more days at 90°f or more tend to sit higher on the chart across 20 states: a pattern in the data, not proof of cause.

• The 6 states with the most very hot days (Arizona, Texas, Florida, Georgia, South Carolina, California): reports of this repair run 35% above what the makes sold there would predict, and 5 of 6 are above expected. The 6 with the least (New York, Michigan, Massachusetts, Pennsylvania, Washington, Ohio): 20% below, and 1 of 6 are above expected.
• Exceptions: South Carolina is among the highest in very hot days but reports below expected.
• Split the states into thirds: the third with the least very hot days runs 20% below what the makes sold there would predict, the middle third 1% below, and the third with the most 35% above. It steps up steadily.
• For very hot days, after allowing for the 1562 comparisons we ran, luck alone would produce a pattern this strong about 1 time in 38. Take out any single state and the very hot days pattern still holds.
• Weak spot: compare only states with similar all-sky sunshine at the surface, kWh per square meter per day and the pattern keeps about 0% of its strength, so part of it may come from all-sky sunshine at the surface, kWh per square meter per day instead of very hot days.

Heat shortens the life of batteries, coolant, hoses, belts and tires.

Source: NOAA U.S. Climate Normals 1991–2020, joined to NHTSA owner complaints · file downloaded 2026-10-06