Home View from Underground Inside the subway’s air conditioning problem

Inside the subway’s air conditioning problem

by Benjamin Kabak

The R-17, shown here in operation as the Shuttle in 1982, was the first subway car outfitted with air condition. (Photo via Steve Zabel at NYCSubway.org)

Needless to say, it’s been a wee bit hot out in New York City. As the heat wave finally crests so that temperatures are a cool 80 degrees as I write it, the heat has settled into the city like an unwelcome house guest. It fills every nook and cranny with uncomfortably stale air and the smells of New York in the summer. It is indeed a pity the days can’t be like the nights.

New Yorkers though have a special dread of summer. It’s hot outside, but it’s worse underground. The heat traps of the subway system, made even warmer with the exhaust from subway cars pushing the mercury up higher, create unpleasant rides on a good day. At least, we think, the air conditioned subway cars offer a respite from the warmth. But what if it all goes wrong?

For a while on the site, when summer dawned, I would dive into the history of bringing air conditioners to the subway system. We haven’t yet solved the platform problem (although new deep-bore stations offer climate control), but after three decades of starts and stops, the MTA introduced a fully air conditioned fleet of subway cars by the mid-1980s. The ceiling fans seen in the old rolling stock at the Transit Museum seem simply quaint these days.

Lately, though, certain air conditioners have begun to fail. Most notably, the single-compressor units in the R62A cars — what you might know as the 1 and 6 trains — have been plagued with outages. The problems began in bits and spurts a few years ago, but with the sustained heat, the issue has exploded in a wave of Tweets directed toward @NYCTSubway, and a transit agency that can’t do too much more than acknowledge the problem.

Kate Hinds at WNYC has covered this story tirelessly this summer because she, like the rest of us, is wary of getting into the so-called hot cars. In late July, when she first wrote about the problem, the MTA explained that they field reports via social media, log them and try to figure out when to address them. The R62As are particularly prone to outages. These 30-year-old cars are due up for scheduled maintenance and have one compressor rather than multi-unit HVAC systems which are easier to repair. They’re old; they break.

But the problem has been the repeat offenders. Hinds revisited the story this week, and either the problem is growing or people are paying more attention. The MTA, which still claims only around 12 reports today, has fielded upwards of 30 air conditioner complaints on Twitter each day this week, and may cars are repeat offenders with early reports stretching back to mid July or even early June. Simply put, the problem is not going away.

Again, these issues are two-fold. First, the MTA doesn’t have the leeway to take one car out of service. Due to the way trainsets are coupled, removing one car from service basically torpedoes half of a ten-car train set. If the MTA took all of the problematic cars out of service, it wouldn’t have nearly enough rolling stock for peak hour demand. (By my count, at this point, around 40 or more different 1 and 6 train cars have been flagged for AC outages. I’m sure more hot cars are out there that haven’t been reported yet.) Second, while the MTA acknowledges that the R62As need scheduled maintenance, the SMS process can take nearly two years. These cars aren’t getting fixed overnight.

It’s bad solution to a design problem that isn’t getting fixed any time soon. We’re going to be hearing about hot cars until the R62As all undergo scheduled maintenance, but it would behoove the MTA to be upfront about this. Right now, they’re asking New Yorkers to report hot cars but are essentially saying that we have to keep riding them until the agency can find a solution. Beware then those emptier cars in an otherwise crowded train. It’s going to be hot in there.

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Duke August 19, 2016 - 12:32 am

It’s worth noting that the useful life of an air conditioning system is considerably shorter than the useful life of a subway car. Honestly, the fact that the MTA has 31 year old air conditioners where most of the units are still functional is an impressive achievement.

A testament to their skills at maintaining ancient equipment long past its expiration date, which they have a lot of experience doing.

Spendmore Wastemor August 19, 2016 - 12:09 pm

The old, not-ozone-friendly charged systems could last upwards of 30 years in stationary usage. Subway cars move, obviously, but there’s not too many potholes in a steel rail, and the system were presumably hardened for mobile use.
I recall a fridge from around WWII that was still running in 2000; couldn’t take it along when I moved, unfortunately.
They don’t make ’em to last that long no mo.

bigbellymon4 August 19, 2016 - 3:14 am

When the scheduled maintenance comes around for the R62A, they should at least see if it is possible to add HVAC systems. That would help make it easier to maintain in the long run.

On a side note, they could add CBTC to R62A’s during the scheduled maintenance to make the entire A Division CBTC-compatible, as the R142/A’s are already compatible. “Two birds. One stone.”

Alex August 19, 2016 - 12:27 pm

Although thoae are great ideas, unfortunately the way those cars were designed in the 80s prevents them.
For the HVACs, these cars were originally designed as “one-car units” for the operational flexibility that was needed at the time. The thing with single car untis is that everything needed to make the car run is squeezed into the one car (instead of spreading out the componants across 2 to 5 cars. Adding a second compressor designed specifically for those cars wont fit. And componants not fitting brings up the cbtc……
For the CBTC, lets use the 7 lines R188 (and converted R142 cars) as a perfect example. When the MTA designed the 142s in the late 90s, they had cbyc in mind. The cars were designed to allow space for its installation. And of you ride the 7, you can still see that some of the cbtc equipment was added inside the passenger area as well (right inside the cars next to the very first side door behind the operator’s cab). Now if they camt add a second compressor to the older fleet, they definitely cant add cbtc equipment.

Larry Littlefield August 19, 2016 - 6:34 am

“It’s bad solution to a design problem that isn’t getting fixed any time soon.”

Actually, with the future open car sets its going to worse. Not only will it be necessary to take half a train out of service to fix one car, it will be necessary to take out the whole thing.

For a bigger and worse issue, check out chart 10.


Subway mean distance between failure is falling on a 12 month moving average basis, which smooths out any one month hiccup. Those reading here know what the increase in MDBF meant to the recovery of the subway system.

It is as if NYC violent crime was soaring on a 12 month moving average basis month after month, and no one talked about it.

CampDavidVIP August 19, 2016 - 11:47 am

Your comment is wrong.

R211 will be 5 car sets so it will only be half a train taken out of service.

Also, air conditioning units are mounted to the top of the trains. They take them off the train and drop a replacement in while the work on the broken ones. Not usually too much time out of service.

Larry Littlefield August 19, 2016 - 1:43 pm

Well that’s good news. But the point is, there are tradeoffs. More room, but still five car sets, although I guess that makes more sense than less room and five car sets.

Meanwhile, why is MDBF falling?

Nando Grumbach August 19, 2016 - 4:10 pm

NOP, AC units are not on top of trains.

Duke August 19, 2016 - 10:43 pm

Here’s what I find even more concerning about that – check out the breakdown by car model on page 30. While the R32s have the single worst decline in reliability (41.5%), second and third place go to the R142A and R143 cars (34.6% and 31.2%, respectively), with the R160s also seeing a 20.5% decline.

Now, one years worth of data may not represent an overall trend but as of this report some of the system’s largest declines in mechanical reliability are coming from some of its newest equipment.

As it is, the R142A and R143 cars are already statistically less reliable than every older model still in service except the R32 and R42. If this trend continues it does not bode well going forward.

I do wonder what their most common modes of failure are, and how many of them have anything to do with the fancy electronics in the newer cars.

Peter L August 19, 2016 - 9:22 am

”Simply put, the problem is going away.”


Benjamin Kabak August 19, 2016 - 9:32 am

Oops! Fixed it.

Chet August 19, 2016 - 11:19 am

The cars on the 1 are 30 years old?! Wow… I remember when they were brand new.

Larry Littlefield August 19, 2016 - 1:43 pm

Yup. Only 20 more years to pay off the bonds.

Chet August 19, 2016 - 3:33 pm

(Seriously… 50 year bonds?)

Larry Littlefield August 21, 2016 - 7:58 pm

They issued 30 year bonds about the time the cars were bought, and then re-borrowed the same money for 30 more years in 2000.


“A top finance analyst for the Legislature added: ”Would I, as a matter of public policy, choose to do this? No, absolutely not. But you have to ask, what are the alternatives? This puts $3 billion into the capital program. Where else is that going to come from?”

Even in 2000, with the city, state and country rolling in dough, Generation Greed didn’t want to pay the freight for its share of the ongoing renewal of our transit system. And rationalized the whole thing away.

BruceNY August 20, 2016 - 12:41 pm

Ha Ha! I can remember watching on the news Mayor Ed Koch touring mock-up of the new subway trains on order, and all of the anti-vandalism features being built into them!

Matt August 19, 2016 - 11:31 am

Why is it so warm inside the subway system, underground? This drives me crazy. It should be 50-60°F year round. I assume its a lack of vertical ventilation.

Duke August 19, 2016 - 11:41 am

Caves stay that sort of temperature because they have little air mixing with outside and no significant internal heat sources.

The subway system, by contrast, is ventilated so its temperature goes up and down as the temperature outside does. And it has lots of internal heat sources (trains, lights, people) so it will always be hotter than outside unless it is air conditioned.

AMH August 23, 2016 - 10:57 am

The biggest heat source is the A/C on the trains. It’s a mixed blessing; cooler trains mean hellish platforms.

Spendmore Wastemor August 19, 2016 - 12:18 pm

I wouldn’t hurt if the pawement which forms the roof of most subway tunnels weren’t dull black. There is such a thing as light colored pavement, and even with oil and rubber deposits it’s still far more reflective than weathered asphalt. Along with that, add cooling towers at the high points and intakes at the lows, and you’d get at least a small continuous venting effect.

JJJ August 19, 2016 - 12:44 pm

Naturally, the brand new and very expensive 2nd avenue subway stations will be fully climate controlled, right?

Benjamin Kabak August 19, 2016 - 12:46 pm

Similar to the new 7 line station, yes.

BruceNY August 20, 2016 - 12:43 pm

Hmm, I wonder if that means that there will be very long escalators from mezzanine to the street, yet not a single escalator down to the platform (like Hudson Yards)?

JJJJ August 22, 2016 - 10:12 am


Aki August 19, 2016 - 1:49 pm

To compliment what you write here…I have a list of weak/broken AC R68 cars in my Google Keep for almost 3 years. Many broken AC R68 cars have a common problem of unbelievably hot car seats. I have been in Japan and always admire their heated car seats during the winter. The broken AC R68 cars is exactly like that, but at the wrong time.

What’s more irony is that during the winter, R68 D trains are among the coldest car I have ever been on. When the temp outside dropped into teens, I have to put everything on to not make myself shivering inside the car. As one would expect, I never feel the warmth of car seats in winter!

It’s also very interesting that although this problem has been there for years (at least on D), it was never mentioned until recently, because, the daring 1 and 6 trains got this problem. And for 6, I know MTA is now using the old 7 fleet on it, so no wondering why it was not brought up when 7 is running R62As…

John-2 August 19, 2016 - 3:50 pm

The irony here is that with the AC problems with the R-32 on the B division, the MTA has a partial summer fix of putting them on the J/Z line that operated mostly outdoors, so that the problems the run into due to the heat in the tunnels on the C line aren’t a factor.

But on the A division, the only line that’s even remotely equivalent to the J/Z in terms of outdoor running is the line the R-62As were just taken off of — the 7. All the other lines have some outdoor running, but mostly stay underground, and even though CBTC hasn’t been implemented yet on the Flushing line so that hypothetically the hottest R-62As could be moved back there again, the six-car sets that are part of the R-188 fleet make it impossible to run them anyplace else but on the 7

(The next least-bad option, I suppose, would be to put the hot cars on the 5, only because it’s not a 24/7 line and those cars could be taken out of service a little more than the trains on the 1/2/3/4/6. But even there you run into the problem of where to store them, since the 5 shares its yard space and the R-142 cars with the 2.)

BrooklynBus August 23, 2016 - 8:51 pm

The MTA definitely has made improvements in terms of maintenance. Although, the R40s were delivered as air conditioned, for many years before they were overhauled, the A/C was functioning on only 10 to 20 percent of the fleet. It was especially uncomfortable since there weren’t any fans and only a small portion of the windows opened.

Nathan Stodola September 5, 2016 - 11:08 am

I was just in London, and realized New York is somewhat lucky to have Air Conditioning at all. Many of the lines on the London Underground (Piccadilly, Central, for instance) have no AC at all. It’s not quite as warm there, but there’s still a few weeks each year that unpleasant is just the beginning of the story.


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