the heater blows cold air on driver dash vent and slightly warm air on passenger side dash vent, I checked under the dash on passenger side and both inlet and outlet tubes going into heater core are extremely hot to the touch. any ideas?

 

Have you changed the Cabin Air Filter since owning the car?

 

no, i have not changed the cabin air filter. Where is it located? Is it difficult to get to?

 

Very easy it's just behind the glovebox. From memory, I think there's a couple of pegs that stop the glovebox opening too far. You either remove them or squeeze the sides of the box inwards (I'm sure I'll be corrected) then let the box come forwards. There's a removable cover directly behind and the filter's in there.

However, if you've got air blowing from the vents it's not the filter. It's more likely to be the motor that controls the air mix flap. You'll need to take it to a dealer and get them to put the diagnostics on it.

 

checked the temp control switch by holding down the radio "ON" button and the radio "SCAN UP" button at the same time which turns on the diagnostics for the temp control switch. The temp control switch moves properly one increment at a time from 1 to 16 as I turn the temp control switch. I looked under the dash on the driver side while someone else pushed each of the ac/heater controls and noted that the actuators move with change in control. We took the car to a dealer who told us the heater core needed flushing. I did not believe him since both the inlet and outlet tubes are extremely hot coming out of the heater core. I took the car to a second dealer who agreed with me that he didn't think it was the heater core. After the second dealer checked the car, he apologized and said it does look like it is a plugged heater core and the inlet and outlet tubes can both be hot because there is a bypass capability of the water flow from the inlet tube to the outlet tube on the same side of the heater core. The second dealer recommended changing out the heater core for over $1,000. I plan to flush the system myself tomorrow.

 

i have not changed the cabin air filter. Where is it located? Is it difficult to get to?

 

I have had similar problems with my 2004 and it is now at the point where when the air is on, it will just stop cold air and blow hot and when the heat is on it will stop hot air and blow cold. It can usually be resolved (temporary) by moving the temp control **** back and forth. I just read an article on carquest that describes a problem that starts with a temperature control problem, the author says it is a problem with a cracked center panel circuit board that is an issue with the RX8
the address of the article is "You need to scroll down to the Mazda article" http://www.carquest.com/cti/proCTISweetSour.pdf
so see what you think about what he has to say. I guess there is an aftermarket replacement panel that is a $ saver. I plan on waiting to see if I end up with a blank display screen or an inoperative A/C b4 I decide to try this. For now, I just tollerate it and when needed I turn the temp **** back and forth.

 

did The flush work ? Because I have the same problem with my rx8 both hoses are hot but cold air inside the cabinet and after 30min of driving it gets warmer but only on one side the driver side still cold .