A machine is usually believed to run both hot and cold at different times if it’s streaky.
http://www.prepody.ru/topic39494.html
http://horsecity.ru/phpBB3/viewtopic.php?f=13&t=255215
http://biopharmamash.com/viewtopic.php?t=1587389
https://www.ww2.site/forum/viewtopic.php?t=180362
http://www.prepody.ru/topic70219.html
http://forum3.bandingklub.cz/viewtopic.php?f=21&t=1681973
http://horsecity.ru/phpBB3/viewtopic.php?f=29&t=171038
https://debate.socialism.nl/forum/showthread.php?tid=307244
https://nauc.info/forums/viewtopic.php?t=22211851
http://gwenael.free.fr/diss3/viewtopic.php?f=8&t=11573
http://forum.ruchkontroliwyborow.pl/index.php?topic=47743.new#new
https://phantom.everburninglight.org/archbbs/viewtopic.php?pid=759659#p759659