Toronto subway riders who want to escape the heat may find that's easier said than done this summer on Line 2 Bloor-Danforth, because the TTC has a problem with what it calls "hot cars" on that line.

The TTC says it is working to fix almost 25 per cent of its subway cars because their air conditioning systems have broken down or are not operating at full capacity. The number of cars with faulty air conditioning is about 80.

Susan Sperling, spokesperson for the TTC, says if at first you don't succeed in getting into a fully air-conditioned car, try, try again.

"You are not going to find a train where all of the cars are hot. So either get out and get into the next car or wait for the next train. You'll find one that's cool for sure," she said.

Sperling told CBC News the hot cars cannot be taken out of service because the TTC needs all of its cars during peak periods.

"The cars get pretty hot. And so, when we find a hot car, we try to take it out of service after peak periods, because we unfortunately don't have enough trains to run peak service without all of our cars," she said.

"We don't have an abundance of spare cars. So we take them out, we identify the problem. Sometimes it's a quick fix, sometimes we need to refurbish the entire air conditioning unit."

Sperling said the TTC has crews at more than one work site focused on the hot car problem, which was identified as an issue last year.

"By next year, everything should be fine," she said.

The hot cars are often put in the middle of the train to ensure operators do not suffer from the heat.

"We can't have our operators who are in trains for eight hours a day in super hot cars."

New subway cars are scheduled to be introduced on Line 2 by 2025.

Arnold Ashton, meterologist for Environment Canada, said the long range forecast for Toronto calls for a warmer and drier July than normal and more of the same in August.