Back in the day, New York City subway cars had ceiling fans, not HVAC units, to approximate climate control. When air conditioning was first piloted in a subway car in 1955, a New York Times reporter called it "the dream of every heat-maddened subway sardine."
Sixty years later, all 6,344 subway cars have air conditioning. Unless, of course, the units break down.
That leads to a special "sort of agony" for subway riders, said Harry Stevens, a reporter with The New York World. He was curious as to which subway cars had the most air conditioner breakdowns. So he requested data from the MTA about their performance.
He found roughly 6,500 "hot car" complaints over the past five years.
Dog Days of Summer
Approximate number of hot subway cars by month, 2010-14
The results of his data dive were both unsurprising and somewhat counter-intuitive. "Generally speaking, the older cars tend to get hot more often than the newer cars," Stevens said. The car with the most air conditioner breakdowns is the R32, the model that runs on the C line. They are the fleet's oldest cars.
(Another issue with the C train: the line runs entirely underground, which can be brutal on A/C units on hot days. So the MTA moves newer-model trains onto the C line during the peak of the summer.)
The best performing car, the R143, serves the L train, and is just a dozen years old. But age doesn't determine performance entirely: The R142A cars, which run on the 4 and 6 lines, are also 12 years old. But they break down much more often.
"Summer in the city brings dreaded hot subway cars" (The New York World)
Predicting which lines will have hot cars is not an exact science, so we've made a Field Guide to NYC Subway Cars to help you out.
Should you be without your field guide, a straphanger's best bet for a cool ride is to watch the cars pulling into the station, and then avoid any empty cars. (A vacant car in the summer months, Stevens said, does not signal "your lucky day. It's actually because it's really hot so nobody wants to be on it.")
The worst month is July, when 15 hot cars are reported by riders each day. On really hot days, that number can triple. Like on July 19, 2013, when 54 cars were taken out of service due to air-conditioning repairs, according to the MTA data obtained by Stevens. The high temperature that day? 96 degrees Fahrenheit.
An MTA spokesman said crews check the HVAC systems of each car each day, rebuild older systems and "continuously monitor" subway air conditioning. Stevens admitted that hot cars are uncommon.
"I think you could probably live in the city for years and never find yourself on a hot subway car," Stevens said. "But when you do, it can be pretty miserable."