Metra riders always seem to have something to complain about. “Hot cars” — where the air conditioning has failed — is the latest passenger peeve.

The problem has been especially acute on the BNSF line, Metra’s busiest, with 94 trains carrying 64,000 riders a day between Aurora and Union Station.

That’s the line where complaints of overcrowded trains erupted in June after a new schedule was introduced.

Tempers boil quickly in standing-room-only cars with 90-degree temperatures.

Riders have lit up Twitter with gripes. Here’s a typical one from Friday morning: “@metraBNSF what the hell BSNF Metra? Nearly every other section of this train has a hot car. It feels like a sauna. When is this being fixed?”

Metra’s been getting the message. On Wednesday, Metra’s board of directors summoned the BNSF to explain the cause of the distress. The Fort Worth, Texas-based BNSF Railway operates the line under contract to Metra.

Sherwin Hudson, the head of the BNSF line’s mechanical department, apologized for the problems. He attempted to explain that there were several reasons for the “hot cars,” including a lack of repair shop time availability, a personnel shortage, and clogged condensers on the AC units.

“They clog very easily,” Hudson said. “It is our leading cause.”

On any day, Hudson said, 12 to 14 of the 211 coaches in the BNSF line’s fleet are experiencing problems with air conditioning, with many cars having repeated breakdowns, Hudson explained.

“We are identifying the hot cars … we are getting people trained,” Hudson said. “We are trying to reduce the repeaters.”

Officials also blamed the problem on the aging coach cars, often about 30 years.

Three of Metra’s 11 board members represent areas with BNSF riders, and each took a turn venting over conditions facing passengers they hear from.

Naperville board member John Zediker pointed out that the BNSF Line has had poor on-time performance — below Metra’s goal of 95 percent — for many months.

The delays and overcrowding problems of late were caused by the introduction of a new schedule to accommodate longer turnaround times for trains. The longer turnarounds, or “flips,” were necessitated by the implementation of a new anti-collision safety system known as Positive Train Control, or PTC.

“Between PTC and hot cars, this is the straw that broke the camel’s back,” Zediker complained.

Board member Stephen Palmer of La Grange told Hudson: “Thanks for coming. But we’re taking a lot of heat from customers and I don’t like it when I don’t have an answer for them.”

Steven Messerli, from Aurora, said Metra needs to do a better job of “PTC squared — the positive treatment of customers.”

— Richard Wronski

A version of this story was also posted on Trains magazine’s News Wire.