Sweating passengers even begged the firm live by Twitter to turn off the heating and one commuters claims the stifling heat contributing to her fainting.
A user called Gar tweeted on Wednesday: “ScotRail Hi, with summer fast approaching, would you please tell train drivers that we don’t need the heating on full blast, especially when we are boarded in like cattle.”
Callum Gorrie wrote: “ScotRail no heating on all winter going to work like Jack from the end of Titanic, now spring is here it’s on full blast - fighting a faint.”
Neil Jones wrote: “Maybe today might be a good time to turn the heating off in carriage 74310 ScotRail?”
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He added a picture of the weather forecast, saying it was 13 degrees in Edinburgh.
A user called KnightswoodBear tweeted: “How do we know that spring and the warmer temperatures have arrived? - ScotRail have the heating on full blast on the train.”
Several travellers said they were caught in a Catch 22. A user called RL tweeted: “ScotRail why do all your trains have the heating on?”
ScotRail replied asking if they had notified staff, to which they replied: “How do I do that on a crowded train?”
And Fern tweeted saying: “ScotRail can you tell me why the heaters need to be blasted on the 7.43 East Kilbride to Glasgow Central train on a dry day when it’s 12 degrees outside?
“Are you trying to see how many people will faint?”
One female passenger did faint on Wednesday, blaming her collapse on a combination of heat and overcrowding.
The 25-year-old, who wishes to remain anonymous, said: “It was an extremely busy train and even at Falkirk the Platform staff said to someone at the edge that they were hanging out of the door.
“It just got far too warm and I remember saying to someone that I thought I was going to faint.
“The next thing I knew I was slumped on the floor at the doors with a man, Ed, trying to help me.”
She added: “The train was crushed as it was, but people moved to give me some space. I really needed air when I got to Waverley.”
“It has been ridiculously warm, generally you are struggling for space at peak times anyway and the service on the glasgow to Edinburgh trains have had greatly reduced services over the past few days.
“And the excuses vary from lack of rolling stock to cows being hit.”
“I commute every day, and for £24.70 a day it is a pretty poor service.”
The “Ed” referred to, Ed Turner, tweeted: “Giving first aid to a @ScotRail passenger who fainted on the Queen Street to Edinburgh hot and jam packed train. #morecarriagesplease”
ScotRail declined to comment on the complaints about heating but said in relation to the woman who fainted: “We are sorry to hear about this woman’s experience, and hope she has recovered.
“We would encourage her to get in touch with us to discuss this further.”