heater problem wierd
 

when my heat is on passenger side is fine but driver side blows cold air. ive done the test for the temp control and it worked fine. ive removed the panel under the steering wheel and went through all the hvac controls and everything seems to work fine. btw both sides blow air with the same force just very different temps. i only drive in my 8 in the summer so heat is not heally an issue but i still want to fix it. plus the drv side can get foggy at times and the defroster will only blow cold air. any clues? thanks guys.:banghead:

I'm having the same problem. Did you ever find the fix?

Im having a similar problem lately where I have the heat on but get cold air. If I turn the dial to cold for a minute and then back to warm the heat will then kick in - but not always. Or I can also switch the defroster on for a minute and then off and that does the trick sometimes. I dont know much about how the heater works but it almost seems like there must be something that is sticking or not opening/closing properly. Sometimes just pounding on the dashboard a few times solves the problem too.

Heater Control failing. The solder connection between the knob and the board weakens, and then breaks, sometimes still getting a connection before completely failing. What temp you are stuck on varies, depending on where along the dial the board side was when it was last 'bumped' by the broken end. Due to the universal irony and psycho-graphics of the driver, it tends to get stuck on the heat or cold side you don't want, since it starts breaking where you use it the most.

Seems to happen more frequently in colder climates, probably due to more usage of the knob and heating/cooling stress.

Common issue, lots of threads, and there is a TSB issued by Mazda. If you are still within the normal bumper to bumper warranty, the dealer will fix it for free, although they typically have to order the parts so it will probably be multiple trips. I had 3 weeks last winter with no heat while they ordered the part and all.

Otherwise the fix is detailed out in a DIY in the Tech section, and shouldn't cost you anything more than time and a bit of solder (assuming you have a soldering iron)

If you are looking for confirmation that this is indeed the issue, there is a button sequence, I think with the power to the center dash off, hold the power button and hit the scan up (or maybe seek up), the display should show a number 0 to 16, and the number should change as you turn the knob, 16 for max heat, 0 (or 1?) for max cold. If it flickers at all, doesn't change, doesn't match, or isn't consistent, then the knob connection is failing as above.

I've had this happening to me as well lately. Interesting.

I have this exact problem. Dealer said part is more than $300. I just got promoted to SSgt so maybe now I can afford to fix the damn thing. It's really cold in Oklahoma right now!

Just fix it yourself if you are out of warranty. Far far cheaper than $300, and not all that difficult.

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

I had this problem last year about this time. Took it to the dealer and it was the heater control unit, they fixed it but it only cost me about $150, no i was not in warranty.