After hearing stories about hot and humid trains without ventilation, I start to think even the slightly air conditioned trains are better.
この場合、次のような言い方ができますよ。
ーAfter hearing stories about hot and humid trains without ventilation, I start to think even the slightly air conditioned trains are better.
「通気口のない蒸し暑い電車の話を聞いたら、弱冷車がマシに思えてきたよ」
slightly air conditioned trains で「弱冷房の電車・弱冷車両」と言えます。
ご参考まで！
カナダ 
