I had to recently replace both the temperature and fan speed controls on my 2004 RX-8. They just had cracked and fallen apart. I presumed that the problem was just broken ***** but thats not the case. I have noticed in the summer that i have to flick the temperature control quickly all the way to cold for the A/C to start working.... Occasionally as I am riding along even on smooth roads, the blower immediately starts blowing HOT. A quick counter clockwise turn of the temp control fixes it and it could stay working for weeks. Now its getting colder I notice that the HEAT does not work at all, it just blows cold and I can't get the heat to work at all with the switch flick trick. Am I dealing with one problem here or multiple ???

Anyone else ever experience this type of behavior? Any thoughts ?

 

search is your friend. read this

https://www.rx8club.com/series-i-do-yourself-forum-73/diy-no-heat-repair-heater-control-158200/